Fix PBD wscript to be python3 compatible

libs/pbd/wscript

@@ -112,10 +112,10 @@ def build(bld):
 
     # Library
     if bld.is_defined ('INTERNAL_SHARED_LIBS'):
-        print 'BUILD SHARED LIB'
+        print('BUILD SHARED LIB')
         obj              = bld.shlib(features = 'cxx cxxshlib', source=libpbd_sources)
     else:
-        print 'BUILD STATIC LIB'
+        print('BUILD STATIC LIB')
         obj              = bld.stlib(features = 'cxx cxxstlib', source=libpbd_sources)
         obj.cxxflags     = [ '-fPIC' ]