[LLVM][Examples] Disable broken JIT + plugin tests (AIX, Sparc)

Plugins appear to be broken on AIX, CI fails. There is logic in
CMakeLists for plugins+AIX, but it was never tested before...
Note: when plugins work, also enable tests in Examples/IRTransforms.

There's no Sparc support for JIT tests, so disable the JIT tests in the
examples (copied from ExecutionEngine/lit.local.cfg).

llvm/test/Examples/Kaleidoscope/lit.local.cfg

@@ -2,3 +2,10 @@
 # RISC-V fails due to unresolved softfp functions.
 if not "X86" in config.root.targets or "riscv" in config.target_triple:
     config.unsupported = True
+
+if config.root.native_target in ['Sparc', 'Hexagon']:
+    config.unsupported = True
+
+# ExecutionEngine tests are not expected to pass in a cross-compilation setup.
+if "native" not in config.available_features:
+    config.unsupported = True

llvm/test/Examples/OrcV2Examples/lit.local.cfg

@@ -1,3 +1,10 @@
 # TODO: investigate
 if not "X86" in config.root.targets:
     config.unsupported = True
+
+if config.root.native_target in ['Sparc', 'Hexagon']:
+    config.unsupported = True
+
+# ExecutionEngine tests are not expected to pass in a cross-compilation setup.
+if "native" not in config.available_features:
+    config.unsupported = True

llvm/test/Feature/load_extension.ll

@@ -6,6 +6,8 @@
 ; RUN: llvm-lto2 run %t.o %loadbye %loadnewpmbye -opt-pipeline="goodbye" -wave-goodbye -o %t -r %t.o,somefunk,plx -r %t.o,junk,plx 2>&1 | FileCheck %s
 ; REQUIRES: plugins, examples
 ; UNSUPPORTED: target={{.*windows.*}}
+; Plugins are currently broken on AIX, at least in the CI.
+; XFAIL: target={{.*}}-aix{{.*}}
 ; CHECK: Bye
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"