[compiler-rt] [compiler-rt] [sanitizer_common] Fix SIGSEGV in ForEachMappedRegion for DSOs with custom image base (PR #206299)

[Thurston Dang via llvm-commits]

thurstond wrote:

I was unable to repro locally with `ninja runtimes-test-depends` (though the buildbot error message is undoubtedly related to this pull request - I'm not sure what's different with my build configuration).

https://github.com/llvm/llvm-project/pull/206299