wayland: Add support for stable xdg-shell

This commit adds support for xdg_shell (the stable version). This was
done by first copying the old xdg-shell unstable v6 implementation into
a separate .c .h file pair (including various symbol renaming) then
porting the old xdg-shell unstable v6 implementation to the new stable
version.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/5
https://bugzilla.gnome.org/show_bug.cgi?id=791938

.gitignore

@@ -98,6 +98,8 @@ src/keyboard-shortcuts-inhibit-unstable-v*-protocol.c
 src/keyboard-shortcuts-inhibit-unstable-v*-server-protocol.h
 src/linux-dmabuf-unstable-v*-protocol.c
 src/linux-dmabuf-unstable-v*-server-protocol.h
+src/xdg-shell-protocol.c
+src/xdg-shell-server-protocol.h
 src/meta/meta-version.h
 src/libmutter-*.pc
 doc/reference/*.args

src/Makefile.am

@@ -68,6 +68,8 @@ mutter_built_sources += \
 	gtk-shell-server-protocol.h		\
 	gtk-primary-selection-protocol.c				\
 	gtk-primary-selection-server-protocol.h				\
+	xdg-shell-protocol.c						\
+	xdg-shell-server-protocol.h					\
 	xdg-shell-unstable-v6-protocol.c				\
 	xdg-shell-unstable-v6-server-protocol.h				\
 	relative-pointer-unstable-v1-protocol.c				\
@@ -454,6 +456,8 @@ libmutter_@LIBMUTTER_API_VERSION@_la_SOURCES +=	\
 	wayland/meta-window-xwayland.h		\
 	wayland/meta-wayland-xdg-shell.c	\
 	wayland/meta-wayland-xdg-shell.h	\
+	wayland/meta-wayland-legacy-xdg-shell.c	\
+	wayland/meta-wayland-legacy-xdg-shell.h	\
 	wayland/meta-wayland-wl-shell.c		\
 	wayland/meta-wayland-wl-shell.h		\
 	wayland/meta-wayland-gtk-shell.c	\
@@ -742,7 +746,7 @@ backends/native/meta-default-modes.h: backends/native/gen-default-modes.py Makef
 .SECONDEXPANSION:
 
 define protostability
-$(shell echo $1 | sed 's/.*\(\<unstable\>\|\<stable\>\).*/\1/')
+$(if $(findstring unstable,$1),unstable,stable)
 endef
 
 define protoname