openbsc: Ignore generated coverage analysis files

This patch adds *.gcda and *.gcno to .gitignore to skip files that
are generated by gcc --coverage and related tools.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/.gitignore b/openbsc/.gitignore
index c08495f..4bfa27d 100644
--- a/openbsc/.gitignore
+++ b/openbsc/.gitignore
@@ -14,6 +14,8 @@
 *.sw?
 .libs
 *.pyc
+*.gcda
+*.gcno
 
 #configure
 aclocal.m4