Fix for PR24072:
X86 instructions jrcxz/jecxz/jcxz performs short jumps if rcx/ecx/cx register is 0
The maximum relative offset for a forward short jump is 127 Bytes (0x7F).
The maximum relative offset for a backward short jump is 128 Bytes (0x80).
Gnu assembler warns when the distance of the jump exceeds the maximum but llvm-as does not.
Patch by Konstantin Belochapka and Alexey Lapshin
Differential Revision: https://reviews.llvm.org/D70652
Alexey Lapshin