Wildcardify kernel toolchain nomenclature turd-sandwhich

finds first prefix's gcc that actually exists, and then substitutes away the gcc suffix

Change-Id: I7d5485ee6a382854e5c98eae554514b0f3462307
[WIP]: New changes needed for msm-3.5 clang

Change-Id: If41682c7265645056be757e58eb14b8707ce7438