[GTK] Make Tools/gtk/generate-gtkdoc compatible with Python 3
https://bugs.webkit.org/show_bug.cgi?id=106195

Reviewed by Philippe Normand.

Perform changes in the generate-gtkdoc script and common and gtkdoc modules
to make the Python code compatible with Python 3. This includes modifying
print statements, exception handling, dictionary iteration and
byte-sequence-to-string conversion.

* gtk/common.py:
(get_build_path):
(pkg_config_file_variable):
(gtk_version_of_pkg_config_file):
* gtk/generate-gtkdoc:
(print_missing_api):
* gtk/gtkdoc.py:
(GTKDoc.__init__):
(GTKDoc._run_command):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139048 268f45cc-cd09-0410-ab3c-d52691b4dbfc