Now that RHEL 5.6 ships with gettext 0.17, we can get out of the
stone age and use the newer gettext capabilities and improved
macros for certain configure tests.

* configure.ac (AM_GNU_GETTEXT_VERSION): Bump to 0.17.
(MKINSTALLDIRS): Delete hack that is no longer needed.
* bootstrap.conf (buildreq): Check for minimum gettext version.
Based on a report by Wen Congyang.