.gitignore: Ignore gcov intermediate files

https://bugzilla.gnome.org/show_bug.cgi?id=725479
diff --git a/.gitignore b/.gitignore
index c084093..ba51c2b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,6 +42,7 @@
 Makefile
 *.gir
 *.typelib
+*.gc??
 
 /gst-libs/gst/pbutils/gstpluginsbaseversion.h
 /gst-libs/gst/tag/mklangtables