[asan] Fix a false positive ODR violation due to LTO ConstantMerge pass [compiler-rt part, take 3]

This fixes a false positive ODR violation that is reported by ASan when using LTO. In cases, where two constant globals have the same value, LTO will merge them, which breaks ASan's ODR detection. See the included testcase for an example.

Differential Revision: https://reviews.llvm.org/D43959

llvm-svn: 327062