libc: Disable FORTIFY if we're using clang-tidy.

Having FORTIFY enabled for clang-tidy adds no value, and breaks some
heuristics for recognizing standard library functions (see the bug).

This also disables FORTIFY for the static analyzer (which we use
through clang-tidy), because it presumably tries to recognize standard
library functions through similar heuristics.

Bug: 36664104
Test: mma with and without the patch to cdefs. New test breaks without.
Change-Id: I40c66ff9e638b306878ada006bc2c98f2346e77a