add yaml-quote for GCE_GLBC_IMAGE

cluster/common.sh

@@ -665,6 +665,7 @@ ENABLE_PATCH_CONVERSION_DETECTOR: $(yaml-quote ${ENABLE_PATCH_CONVERSION_DETECTO
 ADVANCED_AUDIT_POLICY: $(yaml-quote ${ADVANCED_AUDIT_POLICY:-})
 ADVANCED_AUDIT_BACKEND: $(yaml-quote ${ADVANCED_AUDIT_BACKEND:-log})
 GCE_API_ENDPOINT: $(yaml-quote ${GCE_API_ENDPOINT:-})
+GCE_GLBC_IMAGE: $(yaml-quote ${GCE_GLBC_IMAGE:-})
 PROMETHEUS_TO_SD_ENDPOINT: $(yaml-quote ${PROMETHEUS_TO_SD_ENDPOINT:-})
 PROMETHEUS_TO_SD_PREFIX: $(yaml-quote ${PROMETHEUS_TO_SD_PREFIX:-})
 ENABLE_PROMETHEUS_TO_SD: $(yaml-quote ${ENABLE_PROMETHEUS_TO_SD:-false})