Bump version to 2.91.6

Bump to 2.91.6, following Gnome Shell release. Also fixes some
build system bugs, making it possible to make distcheck now.

Makefile.am

@@ -1,3 +1,3 @@
 ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
 
-SUBDIRS = extensions
+SUBDIRS = extensions po

configure.ac

@@ -1,5 +1,5 @@
 AC_PREREQ(2.63)
-AC_INIT([gnome-shell-extensions],[2.91.5],[https://bugzilla.gnome.org/enter_bug.cgi?product=gnome-shell&component=extensions])
+AC_INIT([gnome-shell-extensions],[2.91.6],[https://bugzilla.gnome.org/enter_bug.cgi?product=gnome-shell&component=extensions])
 
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_AUX_DIR([config])

extension.mk

@@ -6,4 +6,5 @@ extensionbase = @gnome-shell-extensions.gnome.org
 
 extensiondir = $(topextensiondir)/$(EXTENSION_ID)$(extensionbase)
 
-extension_DATA = metadata.json extension.js stylesheet.css $(EXTRA_EXTENSION)
+dist_extension_DATA = metadata.json extension.js stylesheet.css
+nodist_extension_DATA = $(EXTRA_EXTENSION)

po/POTFILES.in

@@ -1 +1,4 @@
 extensions/example/extension.js
+extensions/windowsNavigator/extension.js
+extensions/xrandr-indicator/extension.js
+extensions/alternate-tab/extension.js