[TSan] Improve handling of stack pointer mangling in {set,long}jmp, pt.9
[TSan] Improve handling of stack pointer mangling in {set,long}jmp, pt.9

Switch over to computing the xor key in C, instead of assembly for
Linux/AArch64.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@366126 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt