gettext.patch: Update the gettext patch for use with gettext 0.17 which is required to build with libtool 2.2 because...

Original commit message from CVS:
Patch by: Cygwin Ports maintainer
<yselkowitz at users dot sourceforge dot net>
* gettext.patch:
Update the gettext patch for use with gettext 0.17 which is
required to build with libtool 2.2 because of conflicts.
First part of bug #556091.