[clang] [ASAN] Adjust asan instrumented GlobalVariable size to not include redzone (PR #66666)

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b-sumner wrote:

@hctim as far as I'm concerned, the symbol is already not the right size.   The right size of a global variable of type float is 4, not 32.  And disabling ASAN checking in the copy mechanism would reduce the usefulness of the address sanitizer.

But I take your point about linker optimizations.  We are looking at alternatives.

https://github.com/llvm/llvm-project/pull/66666