[Build] Fix coverage build error

- Add `--ignore-errors unused`

Signed-off-by: Yongjoo Ahn <yongjoo1.ahn@samsung.com>

Author: anyj0527

packaging/machine-learning-api.spec

@@ -465,7 +465,7 @@ VCS=`cat ${RPM_SOURCE_DIR}/machine-learning-api.spec | grep "^VCS:" | sed "s|VCS
 pushd build
 # Set different lcov options for Tizen/lcov versions.
 %if 0%{tizen_version_major} >= 9
-lcov -t 'ML API unittest coverage' -o unittest_test.info -c -d . -b $(pwd) --ignore-errors mismatch,empty --exclude "unittest*"
+lcov -t 'ML API unittest coverage' -o unittest_test.info -c -d . -b $(pwd) --ignore-errors mismatch,empty,unused --exclude "unittest*"
 lcov -a unittest_base.info -a unittest_test.info -o unittest_total.info --ignore-errors empty
 lcov -r unittest_total.info "*/tests/*" "*/meson*/*" "*/*@sha/*" "*/*.so.p/*" "*/*tizen*" "*/*-dbus.c" "/usr/*" -o unittest-filtered.info --ignore-errors graph,unused
 %else