[tsan] Derive the unmangled SP in longjmp with xor key on loongarch64

Introducing xor key to derive unmangled sp is here to follow the way
that the glibc adds support for pointer mangling on loongarch in commit
1c9bc1b6e50293a1b7037a7bfbf835868a55baed.

Reviewed By: SixWeining, wangleiat, xen0n

Differential Revision: https://reviews.llvm.org/D146716