Trac #16084: matplotlib dependency on pkgconf

The matplotlib dependency is wrong, this is probably the reason for the
build failure on old OSX versions where it fails to find freetype. If
you build serial / almost serial then pkgconf is not build before
matplotlib. On highly parallel builds, pkgconf finishes much before
matplotlib is started.

URL: http://trac.sagemath.org/16084
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): John Palmieri, Sébastien Labbé

build/deps

@@ -376,7 +376,7 @@ $(INST)/$(TORNADO): $(INST)/$(PYTHON)
 $(INST)/$(MATPLOTLIB): $(INST)/$(PYTHON) $(INST)/$(NUMPY) \
 		       $(INST)/$(FREETYPE) $(INST)/$(LIBPNG) \
 		       $(INST)/$(GDMODULE) $(INST)/$(DATEUTIL) \
-		       $(INST)/$(PKGCONFIG) $(INST)/$(PYPARSING) \
+		       $(INST)/$(PKGCONF) $(INST)/$(PYPARSING) \
                        $(INST)/$(SETUPTOOLS)
 	+$(PIPE) "$(SAGE_SPKG) $(MATPLOTLIB) 2>&1" "tee -a $(SAGE_LOGS)/$(MATPLOTLIB).log"