[llvm] [ASAN] Add "asan_instrumented" llvm ir attribute to identify AddressSanitizer instrumented globals (PR #68865)

[Mitch Phillips via llvm-commits]

hctim wrote:

GlobalVariable sanitization is done as a subset of `SanitizerMetadata` (what you've touched here is the sanitizer attributes for functions). You can take a look at 8db981d463ee2 which should guide you to the right IR and bitcode printing/parsing logic.

Other than that, can you please make the "we increased the global variable size" names non-asan-specific? We also increase GV size on `-fsanitize=hwaddress` and `-fsanitize=memtag-globals` as well. Maybe an appropriate name is `sanitized_padded_global` (or something like that).


https://github.com/llvm/llvm-project/pull/68865