tree fc04162697690792fc8a99c6e2644dc196d00fbb
parent 602c8e0971160e4b85b08b16cf8a2375aa24bc04
author Sara Golemon <sgolemon@fb.com> 1408392399 -0700
committer Jason Evans <je@fb.com> 1408745961 -0700

Test for availability of malloc hooks via autoconf

__*_hook() is glibc, but on at least one glibc platform (homebrew),
the __GLIBC__ define isn't set correctly and we miss being able to
use these hooks.

Do a feature test for it during configuration so that we enable it
anywhere the hooks are actually available.