[lit] Pass LLVM_PROFILE_FILE environment

When building a PGO version of LLVM you might want to customize
the output profile file when building tests. For this to work
we need to pass LLVM_PROFILE_FILE enviroment.

Reviewed By: abrachet

Differential Revision: https://reviews.llvm.org/D143556

Author: tru

llvm/utils/lit/lit/TestingConfig.py

@@ -30,6 +30,7 @@ def fromdefaults(litConfig):
             'LLDB',
             'LD_PRELOAD',
             'LLVM_SYMBOLIZER_PATH',
+            'LLVM_PROFILE_FILE',
             'ASAN_SYMBOLIZER_PATH',
             'HWASAN_SYMBOLIZER_PATH',
             'LSAN_SYMBOLIZER_PATH',