[clang-tools-extra] Remove 'REQUIRES: shell' from lit tests. (#156950)

As preparation for making lit use the internal shell by default in
clang-tools-extra (with significant expected performance gains), this
removes 'REQUIRES: shell' from the clang-tools-extra lit tests that have
it, and updates the one test that was not passing with
'LIT_USE_INTERNAL_SHELL=1' to now pass with the internal shell.

clang-tools-extra/test/clang-include-fixer/multiple_fixes.cpp

@@ -1,4 +1,3 @@
-// REQUIRES: shell
 // RUN: sed -e 's#//.*$##' %s > %t.cpp
 // RUN: mkdir -p %t.dir/clang-include-fixer/multiple-fixes
 // RUN: echo 'foo f;' > %t.dir/clang-include-fixer/multiple-fixes/foo.cpp

clang-tools-extra/test/clang-tidy/infrastructure/clang-tidy-diff.cpp

@@ -1,4 +1,4 @@
-// REQUIRES: shell
+// UNSUPPORTED: system-windows
 // RUN: sed 's/placeholder_for_f/f/' %s > %t.cpp
 // RUN: clang-tidy -checks=-*,modernize-use-override %t.cpp -- -std=c++11 | FileCheck -check-prefix=CHECK-SANITY %s
 // RUN: not diff -U0 %s %t.cpp | %clang_tidy_diff -checks=-*,modernize-use-override -- -std=c++11 2>&1 | FileCheck %s --check-prefixes=CHECK,CHECK-JMAX

clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp

@@ -1,5 +1,3 @@
-// REQUIRES: shell
-
 // RUN: rm -rf %t
 // RUN: mkdir -p %t/dir1/dir2
 // RUN: echo 'class A { A(int); };' > %t/dir1/header.h

clang-tools-extra/test/clang-tidy/infrastructure/header-filter-from-config-file/inheritance/subfolder/bar.cpp

@@ -1,6 +1,8 @@
-// shell is required for the "dirname" command
-// REQUIRES: shell
-// RUN: clang-tidy -checks=-*,google-explicit-constructor %s -- -I "$(dirname %S)" 2>&1 | FileCheck %s
+// UNSUPPORTED: system-windows
+// RUN: pushd %S
+// RUN: cd ..
+// RUN: clang-tidy -checks=-*,google-explicit-constructor %s -- -I "." 2>&1 | FileCheck %s
+// RUN: popd
 #include "foo.h"
 // CHECK-NOT: foo.h:1:12: warning: single-argument constructors must be marked explicit
 

clang-tools-extra/test/clang-tidy/infrastructure/pr37091.cpp

@@ -1,4 +1,3 @@
-// REQUIRES: shell
 // RUN: rm -rf %t
 // RUN: mkdir -p %t
 

clang-tools-extra/test/clang-tidy/infrastructure/vfsoverlay.cpp

@@ -1,6 +1,6 @@
+// UNSUPPORTED: system-windows
 // RUN: sed -e "s:INPUT_DIR:%S/Inputs/vfsoverlay:g" -e "s:OUT_DIR:%t:g" %S/Inputs/vfsoverlay/vfsoverlay.yaml > %t.yaml
 // RUN: clang-tidy %s -checks='-*,modernize-use-nullptr' -vfsoverlay %t.yaml -- -I %t | FileCheck %s
-// REQUIRES: shell
 
 #include "not_real.h"