googletest: default-disable on all of MIPS for now

Parts of the fusefs tests trigger a bug in current versions of llvm: IR
representation of some routine for the MIPS targets is a function with a
large number of arguments. This then leads the compiler on an hour+ long
goose chase, which is OK if you build the current tree but less-so if you're
trying external toolchain or doing a universe build involving mips when it
eventually gets switched over to LLVM.

Better, accurate details can be found in LLVM PR43263.