* move fmaq from freestanding libc to compiler_rt, unconditionally
   exported weak_odr.
 * stage1: add fmaf, fmal, fmaq as symbols that compiler-rt might
   generate calls to.
 * stage1: lower `@mulAdd` directly to a call to `fmaq` instead of to
   the LLVM intrinsic because LLVM will lower it to `fmal` even when the
   target's `long double` is not equivalent to `f128`.

This commit is intended to fix the test suite which is failing on the
previous commit.