shellcheck fix

Author: elek

hadoop-ozone/dev-support/checks/_mvn_unit_report.sh

@@ -27,7 +27,7 @@ find "." -name "*.hprof" -exec cp {} "$REPORT_DIR/" \;
 find "." -name "*.dump" -exec cp {} "$REPORT_DIR/" \;
 
 ## Add the tests where the JVM is crashed
-grep -A1 'Crashed tests' ${REPORT_DIR}/output.log \
+grep -A1 'Crashed tests' "${REPORT_DIR}/output.log" \
   | grep -v -e 'Crashed tests' -e '--' \
   | cut -f2- -d' ' \
   | sort -u >> "${REPORT_DIR}/summary.txt"