[compiler-rt] asan_static x86-64: Support 64-bit ASAN_SHADOW_OFFSET_CONST (PR #75748)

[Brad Smith via llvm-commits]

brad0 wrote:

> I can confirm that [966d564](https://github.com/llvm/llvm-project/commit/966d564e43e650b9c34f9c67829d3947f52add91) builds compiler-rt successfully, while its predecessor ([af837d4](https://github.com/llvm/llvm-project/commit/af837d44c7e126eca16426531ed54d94083f3359)) does not. Thanks @dankm and @MaskRay !

Same for me. Thanks.

https://github.com/llvm/llvm-project/pull/75748