[compiler-rt] Sanitizer/MIPS: fix build fail on pre-R6 (PR #76894)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> On MIPS pre-R6, instruction b can only work within 64KiB,

I left a comment on the Phabricator instance (which I cannot access now) that this is 128KiB.

https://github.com/llvm/llvm-project/pull/76894