gitignore: Add GNU GLOBAL files to top .gitignore

Ignore GPATH, GRTAGS, GSYMS, and GTAGS generated by GNU GLOBAL.

Signed-off-by: Jani Nikula <ext-jani.1.nikula@nokia.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

.gitignore

diff --git a/.gitignore b/.gitignore
index 3433d7c..f3b09fe 100644
--- a/.gitignore
+++ b/.gitignore
@@ -63,6 +63,12 @@
 cscope.*
 ncscope.*
 
+# gnu global files
+GPATH
+GRTAGS
+GSYMS
+GTAGS
+
 *.orig
 *~
 \#*#