Change the order in which GCC is searched
Change the order in which GCC is searched

Instead of using $CC-triple, triple-gcc, $CC, gcc,
Use $CC-triple, $CC, triple-gcc, gcc.

Makes it easier to override the compiler for every possible triple.

thepowersgang/mrustc,thepowersgang/mrustc,thepowersgang/mrustc,thepowersgang/mrustc,thepowersgang/mrustc