non-root make install PREFIX=/tmp fails.

Prepend libdir when executing mkpkgconfig allowing non-root installs to work.

(closes issue #17268)
Reported by: pabelanger
Patches:
      issue17268.patch uploaded by pabelanger (license 224)
Tested by: pabelanger



git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@260661 65c4cc65-6c06-0410-ace0-fbb531ad65f3

Makefile

@@ -413,7 +413,7 @@ distclean: $(SUBDIRS_DIST_CLEAN) _clean
 	rm -f build_tools/menuselect-deps
 
 datafiles: _all
-	CFLAGS="$(_ASTCFLAGS) $(ASTCFLAGS)" build_tools/mkpkgconfig $(DESTDIR)/usr/lib/pkgconfig;
+	CFLAGS="$(_ASTCFLAGS) $(ASTCFLAGS)" build_tools/mkpkgconfig $(DESTDIR)$(libdir)/usr/lib/pkgconfig;
 # Should static HTTP be installed during make samples or even with its own target ala
 # webvoicemail?  There are portions here that *could* be customized but might also be
 # improved a lot.  I'll put it here for now.