ci: Add generation of HTML coverage reports using lcov

Change-Id: I877b2c9cd5250f08fd94b2168ff61522aa4df62d
diff --git a/.jenkins.d/30-coverage.sh b/.jenkins.d/30-coverage.sh
index dbc8025..5080266 100755
--- a/.jenkins.d/30-coverage.sh
+++ b/.jenkins.d/30-coverage.sh
@@ -12,4 +12,21 @@
           --filter="$PWD/src" \
           --root=. \
           --xml
+
+    # Generate also a detailed HTML output, but using lcov (better results)
+    lcov --quiet \
+         --capture --no-external \
+         --directory . \
+         --rc lcov_branch_coverage=1 \
+         --output-file build/coverage-with-tests.info
+
+    lcov --quiet \
+         --remove build/coverage-with-tests.info "$PWD/tests/*" \
+         --rc lcov_branch_coverage=1 \
+         --output-file build/coverage.info
+
+    genhtml --legend \
+            --rc genhtml_branch_coverage=1 \
+            build/coverage.info \
+            --output-directory build/coverage
 fi