Reactor: fix using -x86-asm-syntax only on x86 compilations
Reactor: fix using -x86-asm-syntax only on x86 compilations

The LLVM JIT fails loudly when attempting to parse this command line
option when targeting non-x86 CPUs.

Bug: b/157555596
Change-Id: Ic5ddccbdbc86c2f03ded5f4004369ece0100c031
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52488
Presubmit-Ready: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Tested-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Reviewed-by: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>

google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader