[Downstream change][tests] Mark the tests failing with timeout as unsupported

Initial upstream attempt: llvm/llvm-project#126527

Downstream issue: #177

There are some test cases which tend to fail with timeout when
started on heavy loaded shared machines. As our CI machines are
mostly shared, those failures tend to introduce unnecessary
disturbance to our work. It is better to disable those tests.

For more context, please read issue #177.

Author: pawosm-arm

llvm/utils/lit/tests/googletest-timeout.py

@@ -1,4 +1,5 @@
 # REQUIRES: lit-max-individual-test-time
+# UNSUPPORTED: system-linux
 
 ###############################################################################
 # Check tests can hit timeout when set

llvm/utils/lit/tests/max-time.py

@@ -1,4 +1,5 @@
 # UNSUPPORTED: system-windows
+# UNSUPPORTED: system-linux
 
 # Test overall lit timeout (--max-time).
 #

llvm/utils/lit/tests/xunit-output-report-failures-only.py

@@ -1,3 +1,4 @@
+# UNSUPPORTED: system-linux
 ## Check xunit output.
 # RUN: not %{lit} --report-failures-only --xunit-xml-output %t.xunit.xml %{inputs}/xunit-output
 # RUN: FileCheck --input-file=%t.xunit.xml %s

llvm/utils/lit/tests/xunit-output.py

@@ -1,4 +1,5 @@
 # UNSUPPORTED: system-windows
+# UNSUPPORTED: system-linux
 
 # Check xunit output
 # RUN: rm -rf %t.xunit.xml