[asan] fix __sanitizer_cov_with_check to get the correct caller PC. Before...

[asan] fix __sanitizer_cov_with_check to get the correct caller PC. Before this fix the code relied on the fact that the other function (__sanitizer_cov) is inlined. This was true with clang builds on x86, but not true with gcc builds on x86 and on PPC. This caused bot redness after r292862

llvm-svn: 292998