[MemProf][compiler-rt] Add a test to ensure include files do not diverge

Memprof has two include files that are duplicated between LLVM and
compiler-rt. They need to stay in sync to ensure correct functionality,
but the comments can be somewhat easy to miss, which causes fixups like
839ed1b to be needed. This patch adds a
test to ensure that the files are the same between LLVM and compiler-rt
to catch this ideally before commit, but if not, soon afterwards.

compiler-rt/test/profile/check-same-common-code.test

@@ -0,0 +1,6 @@
+;
+; NOTE: if this test fails, please make sure the relevant copies are identical
+; copies of each other.
+;
+; RUN: diff %crt_src/include/profile/MIBEntryDef.inc %llvm_src/include/llvm/ProfileData/MIBEntryDef.inc
+; RUN: diff %crt_src/include/profile/MemProfData.inc %llvm_src/include/llvm/ProfileData/MemProfData.inc