Update gitignore to ignore all meta-* directories

meta-XYZ directories have been manually added in the past, instead
always ignore them unless they are explicitly added

(From OE-Core rev: 3c6e85c653ce176fd2cb5a570e63c8e5da5a4e48)

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

.gitignore

@@ -9,11 +9,9 @@ build*/pyshtables.py
 pstage/
 scripts/oe-git-proxy-socks
 sources/
-meta-darwin
-meta-maemo
-meta-extras
-meta-m2
-meta-prvt*
+meta-*
+!meta-skeleton
+!meta-demoapps
 *.swp
 *.orig
 *.rej