Clean up .gitignore

Meson enforces a separate build dir, so we no longer have to care
about build artifects in the source tree. Same applies for all
the generated crap autotools like to spread around.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2840>

.gitignore

@@ -1,102 +1,5 @@
-build-aux
-compile
-config.h
-config.h.in
-ltmain.sh
-missing
-50-mutter-navigation.xml
-50-mutter-system.xml
-50-mutter-windows.xml
-mutter-wayland.desktop
-*.o
-*.a
-*.lo
-*.la
-.libs
 *.swp
-*.gir
-*.typelib
-*.gmo
-*.make
-*.log
-*.trs
 *~
-POTFILES
-Makevars.template
-po/*.header
-po/*.pot
-po/*.sed
-po/*.sin
-Rules-quot
-libmutter.pc
-mutter
-mutter-restart-helper
-mutter-test-client
-mutter-test-runner
-mutter-test-unit-tests
-mutter-test-headless-start-test
-mutter-all.test
-org.gnome.mutter.gschema.valid
-org.gnome.mutter.gschema.xml
-org.gnome.mutter.wayland.gschema.valid
-org.gnome.mutter.wayland.gschema.xml
-testasyncgetprop
-testboxes
-testgradient
-INSTALL
-meta-enum-types.[ch]
-src/stamp-meta-enum-types.h
-src/meta-dbus-display-config.[ch]
-src/meta-dbus-idle-monitor.[ch]
-src/meta-dbus-login1.[ch]
-src/meta-dbus-remote-desktop.[ch]
-src/meta-dbus-screen-cast.[ch]
-src/gtk-shell-protocol.c
-src/gtk-shell-server-protocol.h
-src/pointer-gestures-unstable-v*-protocol.c
-src/pointer-gestures-unstable-v*-server-protocol.h
-src/relative-pointer-unstable-v*-protocol.c
-src/relative-pointer-unstable-v*-server-protocol.h
-src/pointer-constraints-unstable-v*-protocol.c
-src/pointer-constraints-unstable-v*-server-protocol.h
-src/xdg-foreign-unstable-v*-protocol.c
-src/xdg-foreign-unstable-v*-server-protocol.h
-src/xdg-output-unstable-v1-protocol.c
-src/xdg-output-unstable-v1-server-protocol.h
-src/xwayland-keyboard-grab-unstable-v1-protocol.c
-src/xwayland-keyboard-grab-unstable-v1-server-protocol.h
-src/tablet-unstable-v*-protocol.c
-src/tablet-unstable-v*-server-protocol.h
-src/text-input-unstable-v*-protocol.c
-src/text-input-unstable-v*-server-protocol.h
-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/wayland-eglstream-controller-server-protocol.h
-src/meta/meta-version.h
-src/libmutter-*.pc
-doc/reference/*.args
-doc/reference/*.bak
-doc/reference/*.hierarchy
-doc/reference/*.interfaces
-doc/reference/*.prerequisites
-doc/reference/*.signals
-doc/reference/*.stamp
-doc/reference/html/
-doc/reference/xml/
-doc/reference/meta-decl-list.txt
-doc/reference/meta-decl.txt
-doc/reference/meta-overrides.txt
-doc/reference/meta-undeclared.txt
-doc/reference/meta-undocumented.txt
-doc/reference/meta-unused.txt
-doc/reference/meta-docs.sgml
-doc/reference/meta.types
-.dirstamp
 **/tags.*
-build/
 subprojects/sysprof/
 __pycache__/