[openmp] [test] Set __COMPAT_LAYER=RunAsInvoker when running tests on Windows

[mstorsjo]

Summary

Windows heuristics may decide to want to run some tested processes
as elevated (since it may think some of them are installers - executables
with "dispatch" in the name may hit a heuristic looking for "patch").

Set this environment variable to disable this heuristic and just run
the executable with whatever privileges the caller has.

This fixes a couple tests on such versions of Windows where this
heuristic is active.

[Meinersbur]

since it may think some of them are installers - executables with "dispatch" in the name may hit a heuristic looking for "patch"

Wow, didn't know, but other sources confirm it.

openmp/runtime/test/lit.cfg

111–112

Could you add a comment on what this does?

I did not know about this, but found https://devblogs.microsoft.com/oldnewthing/20161117-00/?p=94735

[mstorsjo]

Rebased, added a comment.

[mstorsjo]

Ping

[jlpeyton]

LGTM

openmp/runtime/test/lit.cfg

if 'Linux' in config.operating_system:
     config.available_features.add("linux")
 
 if config.operating_system == 'NetBSD':
     config.available_features.add("netbsd")
 
 if config.operating_system in ['Linux', 'Windows']:
     config.available_features.add('affinity')
 
 if config.operating_system in ['Linux']:
     config.available_features.add('hidden-helper')
 
+# Avoid Windows heuristics which try to detect potential installer programs
+# (which may need to run with elevated privileges) and ask if the user wants
+# to run them in that way. This heuristic may match for executables containing
+# the word "patch" which is a substring of "dispatch". Set an environment
+# variable indicating that we want to execute them with the current user.
+if config.operating_system == 'Windows':
+    config.environment['__COMPAT_LAYER'] = 'RunAsInvoker'
+
 import multiprocessing
 try:
     if multiprocessing.cpu_count() > 1:
         config.available_features.add('multicpu')
 except NotImplementedError:
     pass
 
 # to run with icc INTEL_LICENSE_FILE must be set