[LNT] Setting CMake variable to support test-suite feature from D53565

[eklepilkina]

Summary

Review https://reviews.llvm.org/D53565 added new CMake variable which allows to generate only needed part of test-suite if user set --only-test.

[fhahn]

Please rebase the patch if it is still relevant.

lnt/tests/test_suite.py

         if self.opts.test_suite_externals:
             defs['TEST_SUITE_EXTERNALS_DIR'] = self.opts.test_suite_externals
         if self.opts.pgo and self.trained:
             defs['TEST_SUITE_PROFILE_USE'] = "On"
             defs['TEST_SUITE_PROFILE_GENERATE'] = "Off"
             if 'TEST_SUITE_RUN_TYPE' not in defs:
                 defs['TEST_SUITE_RUN_TYPE'] = 'ref'
 
+        if self.opts.only_test:
+            defs['BENCH_DIRS'] = self.opts.only_test[0]
+
         for item in tuple(self.opts.cmake_defines) + tuple(extra_cmake_defs):
             k, v = item.split('=', 1)
             # make sure the overriding of the settings above also works
             # when the cmake-define-defined variable has a datatype
             # specified.
             key_no_datatype = k.split(':', 1)[0]
             if key_no_datatype in defs:
                 del defs[key_no_datatype]