When testing sanitizers using GCC as a host compiler, skip most of them
on non-x86-64 targets. This gives the builder a chance of working on
PowerPC64 and other targets which don't have ports of all the sanitizers
yet.

git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@224704 91177308-0d34-0410-b5e6-96231b3b80d8