bootstrap: Fix minimum required version for convert.

ChangeLog

+2011-09-15  Guillaume Lazzara  <z@lrde.epita.fr>
+
+	* bootstrap: Fix minimum required version for convert.
+
 2011-09-15  Guillaume Lazzara  <z@lrde.epita.fr>
 
 	* configure.ac: Handle both GraphicsMagick and ImageMagick.

bootstrap

@@ -154,7 +154,11 @@ export LIBTOOLIZE=$libtoolize
 require $libtoolize 1.5.22
 
 require doxygen 1.5.6
-require convert 6.3.7
+# We used to require `convert' from ImageMagick 6.3.7, but `convert'
+# from GraphicsMagick 1.3.12 is also fine.  Use that later revision
+# number even if ImageMagick is actually used so as to be compatible
+# with both implementations.
+require convert 1.3.12 -version
 require hevea 1.10 -version