common: ignore inconsistent coverage reports

lcov 2.1 added more consistency checks that trip over coverage collected
from systemd, as the coverage collected during shutdown might not be
complete. Let's just ignore the errors for now.

Related: systemd/systemd@238ddac

common/utils.sh

@@ -548,7 +548,9 @@ lcov_collect() {
 # Returns:
 #   0 on success, 1 otherwise (i.e. no reports found, invalid data, etc.)
 lcov_merge() {
-    local lcov_args=()
+    # lcov 2.1 added more consistency checks that trip over coverage collected from systemd, as the coverage
+    # collected during shutdown might not be complete; let's just ignore the errors for now
+    local lcov_args=(--ignore-errors inconsistent)
     local file
     local output_file="${1:?}"
     shift