Disable tests for google-benchmark library build

[MatzeB]

Summary

The tests of the google-benchmark package fail to build on systems
that do not have an executbale named python in the path. Systems like
CentOS only provide python3 nowadays.

This just disables the tests as we don't need them.

[mtrofin]

Could we detect the CentOS case instead of always disabling them - iirc @lebedev.ri pointed out that there is some benefit to having them on.

[MatzeB]

FWIW: I tried fixing things upstream in https://github.com/google/benchmark/pull/1496 but that got reverted in the meantime and I don't have the time to keep pushing on this until all the corner cases work...

[MatzeB]

Looking back at upstream it seems part of my change is still around so updating may help.

That said: This change here simplifies our build and allows us to drop those odd gmock and gtest dependencies. So I still would rather use this cleanup here! Is there really any reason to run google-benchmark tests in the context of llvm-test-suite?

[mtrofin]

In D151917#4388881, @MatzeB wrote:

Looking back at upstream it seems part of my change is still around so updating may help.

That said: This change here simplifies our build and allows us to drop those odd gmock and gtest dependencies. So I still would rather use this cleanup here! Is there really any reason to run google-benchmark tests in the context of llvm-test-suite?

Oh! Fun :)

LGTM, if no one objects too strongly.

MicroBenchmarks/libs/CMakeLists.txt

 # The benchmark library build system uses try_run tests to determine regex
 # Circumvent these tests and enforce std::regex
 set(CMAKE_CXX_STANDARD 11)
 set(HAVE_STD_REGEX 1)
 # When enforcing c++11 we need to disable one of the benchmark library's tests
 set(BENCHMARK_HAS_CXX03_FLAG 0)
+# Tests fail build on system with just "python3" but no "python" executable.
+set(BENCHMARK_ENABLE_GTEST_TESTS OFF)
+set(BENCHMARK_ENABLE_ASSEMBLY_TESTS OFF)
 
 add_subdirectory(benchmark)
 test_suite_add_build_dependencies(benchmark)
-test_suite_add_build_dependencies(output_test_helper)
-test_suite_add_build_dependencies(gtest)
-test_suite_add_build_dependencies(gmock)
-
-# These tests, when built with BENCHMARK_ENABLE_ASSEMBLY_TESTS is on.
-# They don't depend on the above, so we need to list them explicitly.
-if (BENCHMARK_ENABLE_ASSEMBLY_TESTS)
-  test_suite_add_build_dependencies(donotoptimize_assembly_test)
-  test_suite_add_build_dependencies(state_assembly_test)
-  test_suite_add_build_dependencies(clobber_memory_assembly_test)
-endif()
-