The check is for the clang plugin, which is a host library. It is especially
important to use the host compiler for this check on OSX-on-Linux cross builds.
Right now, if the LLVMCONFIG variable is not set in the .mozconfig, we
first look for the system default llvm-config and only then we ask clang
itself, which breaks building with the clang plugin if you make $CC and
$CXX point to a non-default clang binary. This patch fixes the issue
by reversing the search order.
--HG--
extra : rebase_source : 23ab716f4e220097e4c31092475dba769f4e7dfc