[cross-project-tests] Mark llgdb-tests/sret.cpp as UNSUPPORTED on Linux
See https://github.com/llvm/llvm-project/issues/188957
Fails with following error on the `cross-project-tests-sie-ubuntu-dwarf5` builder:
```
******************** TEST 'cross-project-tests :: debuginfo-tests/llgdb-tests/sret.cpp' FAILED ********************
Exit Code: 1
Command Output (stdout):
--
Running debugger
Running FileCheck
Debugger output was:
Breakpoint 1 at 0x11fb: file /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp, line 64.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, B::AInstance (this=0x7fffffffe6ef) at /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp:64
64 A a(12);
$1 = {_vptr$A = 0x0, m_int = 0, static __clang_vtable = <optimized out>}
A debugging session is active.
Inferior 1 [process 1110596] will be killed.
Quit anyway? (y or n) [answered Y; input not from terminal]
--
Command Output (stderr):
--
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/bin/clang --driver-mode=g++ --target=x86_64-unknown-linux-gnu -O0 -g /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp -c -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.o # RUN: at line 4
+ /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/bin/clang --driver-mode=g++ --target=x86_64-unknown-linux-gnu -O0 -g /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp -c -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.o
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/bin/clang --driver-mode=g++ --target=x86_64-unknown-linux-gnu /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.o -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.out # RUN: at line 5
+ /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/bin/clang --driver-mode=g++ --target=x86_64-unknown-linux-gnu /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.o -o /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.out
PYTHON_EXEC_PATH=/usr/bin/python3.10 LLDB_PYTHON_PATH=/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/./lib/python3.10/site-packages /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/test_debuginfo.pl /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.out # RUN: at line 6
+ PYTHON_EXEC_PATH=/usr/bin/python3.10
+ LLDB_PYTHON_PATH=/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/./lib/python3.10/site-packages
+ /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/test_debuginfo.pl /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.tmp.out
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp:14:11: error: CHECK: expected string not found in input
// CHECK: {{(_vptr\$A =)?.*}}m_int = 12
^
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.gdb.output:7:5: note: scanning from here
$1 = {_vptr$A = 0x0, m_int = 0, static __clang_vtable = <optimized out>}
^
/home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.gdb.output:7:6: note: possible intended match here
$1 = {_vptr$A = 0x0, m_int = 0, static __clang_vtable = <optimized out>}
^
Input file: /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/build/projects/cross-project-tests/debuginfo-tests/llgdb-tests/Output/sret.cpp.gdb.output
Check file: /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp
-dump-input=help explains the following input dump.
Input was:
<<<<<<
1: Breakpoint 1 at 0x11fb: file /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp, line 64.
2: [Thread debugging using libthread_db enabled]
3: Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
4:
5: Breakpoint 1, B::AInstance (this=0x7fffffffe6ef) at /home/buildbot/buildbot-root/cross-project-tests-sie-ubuntu-dwarf5/llvm-project/cross-project-tests/debuginfo-tests/llgdb-tests/sret.cpp:64
6: 64 A a(12);
7: $1 = {_vptr$A = 0x0, m_int = 0, static __clang_vtable = <optimized out>}
check:12 ^~~~
check:14'0 X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
check:14'1 ? possible intended match
8: A debugging session is active.
check:14'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9:
check:14'0 ~
10: Inferior 1 [process 1110596] will be killed.
check:14'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
11:
check:14'0 ~
12: Quit anyway? (y or n) [answered Y; input not from terminal]
check:14'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>>>
--
```
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