[OpenMP] Disable libarcher tests for the experimental AMDGPU buildbot

[jhuber6]

Summary

These tests are flaky with the settings that we want to test. We aren't
focused on testing archer and the project seems largely unmaintained
for now. This patch disables support for libarcher so we can keep the
bot green.

[jplehr]

buildbot/osuosl/master/config/builders.py

1886

Are you missing the leading -D here?

[jhuber6]

Fixing typo

[jplehr]

LGTM

buildbot/osuosl/master/config/builders.py

'factory' : OpenMPBuilder.getOpenMPCMakeBuildFactory(
                         extraCmakeArgs=[
                             "-DCMAKE_BUILD_TYPE=Release",
                             "-DCLANG_DEFAULT_LINKER=lld",
                             "-DLLVM_TARGETS_TO_BUILD=X86;AMDGPU",
                             "-DLLVM_ENABLE_ASSERTIONS=ON",
                             "-DCMAKE_C_COMPILER_LAUNCHER=ccache",
                             "-DCMAKE_CXX_COMPILER_LAUNCHER=ccache",
                             "-DLIBOMPTARGET_FOUND_AMDGPU_GPU=ON",
+                            "-DLIBOMP_ARCHER_SUPPORT=OFF",
                             "-DLIBC_GPU_BUILD=ON",
                             "-DLIBC_GPU_ARCHITECTURES=gfx906",
                             "-DLIBC_GPU_TEST_ARCHITECTURE=gfx906",
                             ],
                         install=True,
                         testsuite=False,
                         testsuite_sollvevv=False,
                         extraTestsuiteCmakeArgs=[