[mapnik] Add patch.

[alexlan]

commit 4f33c5e8fb8b985c8a735e1e4ed25a272aeafaca
Author: Alex Lancaster <alexlan[AT]fedoraproject org>
Date:   Mon Apr 29 13:21:28 2013 -0400

    Add patch.

 mapnik-2.1.0-build-viewer.patch |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/mapnik-2.1.0-build-viewer.patch b/mapnik-2.1.0-build-viewer.patch
new file mode 100644
index 0000000..d3025ed
--- /dev/null
+++ b/mapnik-2.1.0-build-viewer.patch
@@ -0,0 +1,20 @@
+diff --git a/demo/viewer/viewer.pro b/demo/viewer/viewer.pro
+index 048cfad..fe0e429 100644
+--- a/demo/viewer/viewer.pro
++++ b/demo/viewer/viewer.pro
+@@ -2,10 +2,11 @@
+ # Mapnik viewer - Copyright (C) 2007 Artem Pavlenko
+ ######################################################################
+ TEMPLATE = app
+-QMAKE_CXX = clang++
+-QMAKE_CXXFLAGS += $$system(mapnik-config --cflags)
+-QMAKE_LFLAGS += $$system(mapnik-config --libs)
+-QMAKE_LFLAGS += $$system(mapnik-config --ldflags --dep-libs)
++QMAKE_CXX = g++
++QMAKE_CXXFLAGS += -I../../include
++QMAKE_CXXFLAGS += $$system(../../utils/mapnik-config/mapnik-config --cflags)
++QMAKE_LFLAGS += -L../../src -l mapnik
++QMAKE_LFLAGS += $$system(../../utils/mapnik-config/mapnik-config --ldflags --dep-libs)
+ 
+ # Input
+