Add FULL_LIB_PATH option for OS X to link in the full path to libmapnik.dylib in the library itself

SConstruct

@@ -156,9 +156,10 @@ opts.AddVariables(
     
     # Other variables
     ('SYSTEM_FONTS','Provide location for python bindings to register fonts (if given aborts installation of bundled DejaVu fonts)',''),
-    ('LIB_DIR_NAME','Name to use for lib folder where fonts and plugins are installed','/mapnik/'),
+    ('LIB_DIR_NAME','Name to use for the "lib" folder 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'),
+    BoolVariable('FULL_LIB_PATH', 'Use the full path for the libmapnik.dylib "install_name" when linking on Mac OS X', 'False'),
     ListVariable('BINDINGS','Language bindings to build','all',['python']),
     EnumVariable('THREADING','Set threading support','multi', ['multi','single']),
     EnumVariable('XMLPARSER','Set xml parser ','libxml2', ['tinyxml','spirit','libxml2']),

src/SConscript

@@ -29,6 +29,8 @@ ABI_VERSION = env['ABI_VERSION']
 
 prefix = env['PREFIX']
 
+lib_dir = os.path.normpath(prefix + '/' + env['LIBDIR_SCHEMA'])
+
 install_prefix = env['DESTDIR'] + '/' + prefix
 
 libraries = env['LIBS']
@@ -37,7 +39,11 @@ if env['INTERNAL_LIBAGG']:
     libraries.insert(0, 'agg')
 
 if env['PLATFORM'] == 'Darwin':
-    linkflags = '-Wl,-install_name,libmapnik.dylib'
+    if env['FULL_LIB_PATH']:
+        lib_path = '%s/libmapnik.dylib' % lib_dir
+    else:
+        lib_path = 'libmapnik.dylib'
+    linkflags = '-Wl,-install_name,%s' % lib_path
 elif env['PLATFORM'] == 'SunOS' and env['CXX'].startswith('CC'):
     linkflags = '-R. -h libmapnik.so'
 else: # Linux and others