I ran into this issue as well some time ago, and my "solution" was to remove those definitions from my local gettext.h copy. It is a non-solution, but I thought I should mention it in case your project (like gsasl) does not use those gettext.h functions and you just want to silence the warning.
http://git.savannah.gnu.org/gitweb/?p=gsasl.git;a=blob;f=gl/override/lib/gettext.h.diff;hb=HEAD /Simon
