autotools: Add code coverage support

Change-Id: I7d11c64ffa3e68973081cfb1f3fdc1817a64e8cd
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/.gitignore b/.gitignore
index 25978d3..9523617 100644
--- a/.gitignore
+++ b/.gitignore
@@ -55,3 +55,5 @@
 # Autotools test infrastructure
 *.log
 *.trs
+*.gcno
+*.gcda