Unbreak the linux bot from the previous commit. Fred needed to use

some of the macros from mach/exc_resource.h to decode EXC_RESOURCE,
but that header doesn't exist on non-apple platforms and
StopInfoMachException.cpp needs to build on those systems.
EXC_RESOURCE won't be decoded when lldb is built on non-darwin systems.

llvm-svn: 346573