Simplify build-gnu.sh

Author: oech3

util/build-gnu.sh

@@ -106,7 +106,7 @@ echo "UU_BUILD_DIR='${UU_BUILD_DIR}'"
 cd "${path_UUTILS}" && echo "[ pwd:'${PWD}' ]"
 
 export SELINUX_ENABLED # Run this script with=1 for testing SELinux
-[ "${SELINUX_ENABLED:-0}" -eq 1 ] && CARGO_FEATURE_FLAGS="${CARGO_FEATURE_FLAGS} selinux"
+[ "${SELINUX_ENABLED}" = 1 ] && CARGO_FEATURE_FLAGS="${CARGO_FEATURE_FLAGS} selinux"
 
 # Trim leading whitespace from feature flags
 CARGO_FEATURE_FLAGS="$(echo "${CARGO_FEATURE_FLAGS}" | sed -e 's/^[[:space:]]*//')"