Log Message:
Rework the way intltool is overriden in packages that use it.  Up until now
we were running intltoolize before the configure stage, which replaced all
intltool-*.in files with symlinks to the ones installed by this package.

However, the new version of intltool, 0.31.3, has added new substitution
patterns to the scripts, which must be replaced by configure scripts at
configuration time.  The problem is that old configure scripts (pre-0.31.3)
do not know about these patterns, which results in them not being substituted,
thus causing build failures.

So, to fix this issue, replace all intltool-* files _after_ the configure
stage, just like we do with libtool.  Additional patters might be added
through the INTLTOOL_OVERRIDE variable, but I doubt this will be needed).

While here, update the dependency to 0.31.3 (has no other effect, as this
package is only used at build time by other packages).