scons: do not invoke any install or uninstall targets if using SYSTEM…

…_FONTS - closes #1481

SConstruct

@@ -350,7 +350,7 @@ opts.AddVariables(
 
     # Other variables
     BoolVariable('SHAPE_MEMORY_MAPPED_FILE', 'Utilize memory-mapped files in Shapefile Plugin (higher memory usage, better performance)', 'True'),
-    ('SYSTEM_FONTS','Provide location for python bindings to register fonts (if given aborts installation of bundled DejaVu fonts)',''),
+    ('SYSTEM_FONTS','Provide location for python bindings to register fonts (if provided then the bundled DejaVu fonts are not installed)',''),
     ('LIB_DIR_NAME','Name to use for the subfolder beside libmapnik where fonts and plugins are installed','mapnik'),
     PathVariable('PYTHON','Full path to Python executable used to build bindings', sys.executable),
     BoolVariable('FRAMEWORK_PYTHON', 'Link against Framework Python on Mac OS X', 'True'),

fonts/build.py

@@ -22,15 +22,12 @@
 
 Import('env')
 
-# grab all the deja vu fonts
-includes = glob.glob('*/*/*.ttf')
-
-# grab single unifont ttf (available at http://unifoundry.com/unifont.html)
-includes.extend(glob.glob('unifont*.ttf'))
-
-target_path = env['MAPNIK_FONTS_DEST']
-
-if 'uninstall' not in COMMAND_LINE_TARGETS and not env['SYSTEM_FONTS']:
-    env.Alias(target='install', source=env.Install(target_path, includes))
-
-env['create_uninstall_target'](env, target_path)
+if not env['SYSTEM_FONTS']:
+    # grab all the deja vu fonts
+    includes = glob.glob('*/*/*.ttf')
+    # grab single unifont ttf (available at http://unifoundry.com/unifont.html)
+    includes.extend(glob.glob('unifont*.ttf'))
+    target_path = env['MAPNIK_FONTS_DEST']
+    if 'uninstall' not in COMMAND_LINE_TARGETS:
+        env.Alias(target='install', source=env.Install(target_path, includes))
+    env['create_uninstall_target'](env, target_path)