Move NSGlView into libgtkmm2ext

This allows to re-use the concept with CairoWidget

libs/canvas/wscript

@@ -3,7 +3,6 @@ from waflib.extras import autowaf as autowaf
 from waflib import Options
 from waflib import TaskGen
 import os
-import sys
 
 # Version of this package (even if built as a child)
 MAJOR = '0'
@@ -97,9 +96,6 @@ def build(bld):
     obj.install_path = bld.env['LIBDIR']
     obj.defines      += [ 'PACKAGE="' + I18N_PACKAGE + '"' ]
 
-    if sys.platform == 'darwin':
-        obj.source += [ 'nsglview.mm']
-
     # canvas unit-tests are outdated
     if False and bld.env['BUILD_TESTS'] and bld.is_defined('HAVE_CPPUNIT'):
             unit_testobj              = bld(features = 'cxx cxxprogram')