This patch fixes an issue on Fedora where if you had the x86_64 cross
compiler installed on your x86_64 system, then clang would use that compiler
as the default toolchain. This was happening because the cross compiler
is installed to /usr/lib/gcc/x86_64-linux-gnu/ and this directory comes before
the default compiler directory (/usr/lib/gcc/x86_64-redhat-linux/) in the search
This patch re-orders the search list so that vendor supplied gcc toolchains
are selected before toolchains with a generic target, which should prevent
these kind of issues on other OSes too.