Avoid automagic detection of dblatex or fop at build time.

Dependencies in Gentoo have to be explicit, not automagic. As gtk-doc
doesn't depend on either dblatex (for which there is no ebuild adding that
binary to the PATH) nor dev-java/fop (which provides a fop binary on the
PATH), gtk-doc should not enable support for either of these at build time.

2012-03-07 Martin von Gagern

References:
https://bugs.gentoo.org/404495

Index: gtk-doc-1.18/configure.ac
===================================================================
--- gtk-doc-1.18.orig/configure.ac
+++ gtk-doc-1.18/configure.ac
@@ -84,15 +84,10 @@ if test -z "$XSLTPROC"; then
 fi
 
 dnl
-dnl Check for dblatex/fop (for pdf output)
+dnl No automagic detection of dblatex/fop (for pdf output)
 dnl
-AC_PATH_PROG([DBLATEX], [dblatex])
-if test -z "$DBLATEX"; then
-	AC_PATH_PROG([FOP], [fop])
-	if test -z "$FOP"; then
-		AC_MSG_WARN([neither dblatex nor fop found, so no pdf output from xml])
-	fi
-fi
+AC_SUBST([DBLATEX],[])
+AC_SUBST([FOP],[])
 
 dnl check for DocBook DTD and stylesheets in the local catalog.
 JH_CHECK_XML_CATALOG([-//OASIS//DTD DocBook XML V4.3//EN], [DocBook XML DTD V4.3])