Add a gitignore file

.gitignore

+*.[ao]
+*.gcda
+*.gcno
+*.gcov
+*.l[ao]
+*.loT
+*.orig
+*.pc
+*.py[co]
+*.rej
+*.sw[op]
+*~
+*#
+.#*
+.deps
+.libs
+Makefile
+Makefile.in
+_gen
+/aclocal.m4
+/autom4te.cache
+/compile
+/config.cache
+/config.guess
+/config.h
+/config.h.in
+/config.log
+/config.status
+/config.sub
+/configure
+/depcomp
+/install-sh
+/libtool
+/ltmain.sh
+/m4
+/missing
+/stamp-h1
+shell/desktop-shell-client-protocol.h
+shell/desktop-shell-protocol.c
+shell/weston-desktop-shell