[CleanUp] Add appropriate suffix to 64-bit literal
[CleanUp] Allow build type to propagate instead of setting to Debug in brig2llvm/CMakeLists.txt, src/CMakeLists.txt and hsa_runtime/CMakeLists.txt
[HSA-678 Fix] Overcome a bug in LLVM that prevent it from recognizing correct target triple,which leads to wrong stack alignment being set.
[Cleanup] Expand comment about llvm::Triple and stack alignment issues.