Clean up more recursive FORTIFY_SOURCE calls

Don't use FORTIFY_SOURCE on functions which implement
FORTIFY_SOURCE, to avoid infinite recursion problems.

The previous patch only addressed one of the problems.

Bug: 12216860
Change-Id: I6f30ae7cb5b481be9942add18182ea4839d348a6
libm: Fix multiple inclusion warning

Change-Id: Ifa732ec52fb582c34512cd1d09d918199ae7395e