Add poky-autobuilder to .gitignore

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

.gitignore

@@ -7,6 +7,7 @@ sources/
 meta-darwin
 meta-maemo
 meta-prvt*
+poky-autobuilder*
 *.swp
 *.orig
 *.rej