Fix build_performance_php7.sh to pass shellcheck

tools/run_tests/performance/build_performance_php7.sh

@@ -15,9 +15,9 @@
 
 set -ex
 
-cd $(dirname $0)/../../..
+cd "$(dirname "$0")/../../.."
 CONFIG=${CONFIG:-opt}
-python tools/run_tests/run_tests.py -l php7 -c $CONFIG --build_only -j 8
+python tools/run_tests/run_tests.py -l php7 -c "$CONFIG" --build_only -j 8
 
 # Set up all dependences needed for PHP QPS test
 cd src/php/tests/qps