Avoid using - (hyphen) in gdbus-codegen directory name

It's an invalid character in Python module names and prevents us from
being able to import it.

https://bugzilla.gnome.org/show_bug.cgi?id=650763

configure.ac

@@ -3841,8 +3841,8 @@ gobject/tests/Makefile
 gthread/Makefile
 gthread/tests/Makefile
 gio/Makefile
-gio/gdbus-codegen/Makefile
-gio/gdbus-codegen/config.py
+gio/gdbus-2.0/codegen/Makefile
+gio/gdbus-2.0/codegen/config.py
 gio/xdgmime/Makefile
 gio/inotify/Makefile
 gio/libasyncns/Makefile

gio/Makefile.am

@@ -2,7 +2,7 @@ include $(top_srcdir)/Makefile.decl
 
 NULL =
 
-SUBDIRS = gdbus-codegen
+SUBDIRS = gdbus-2.0/codegen
 
 if OS_UNIX
 SUBDIRS += libasyncns xdgmime

gio/gdbus-2.0/codegen/Makefile.am

@@ -4,7 +4,7 @@ bin_SCRIPTS =
 CLEANFILES =
 EXTRA_DIST =
 
-codegendir = $(libdir)/gdbus-codegen
+codegendir = $(libdir)/gdbus-2.0/codegen
 codegen_PYTHON =						\
 	__init__.py						\
 	codegen.py						\

gio/gdbus-2.0/codegen/gdbus-codegen.in

@@ -25,7 +25,7 @@
 import os
 import sys
 
-path = os.path.join('@libdir@', 'gdbus-codegen')
+path = os.path.join('@libdir@', 'gdbus-2.0', 'codegen')
 sys.path.insert(0, path)
 
 from codegen_main import codegen_main