build: add code coverage

Add code coverage to build

Change-Id: I198d8bc9e6b99556582c14fc4dfd4c835150b5e0
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/.lcovrc b/.lcovrc
new file mode 100644
index 0000000..360a8b4
--- /dev/null
+++ b/.lcovrc
@@ -0,0 +1,3 @@
+geninfo_gcov_all_blocks = 1
+lcov_function_coverage = 1
+lcov_branch_coverage = 0