Fix free translation error

 Ported from: m2-farzan/ros2-galactic-PKGBUILD#33

PKGBUILD

@@ -61,7 +61,8 @@ prepare() {
 
 build() {
     # Disable parallel build if RAM is low
-    if [[ $(free | grep -Po "Mem:\s+\K\d+") -lt 16000000 ]]; then
+    MIN_PARALLEL_BUILD_RAM_KB=16000000
+    if [[ $(free | grep -Po "Mem:\s+\K\d+") -lt $MIN_PARALLEL_BUILD_RAM_KB && $(grep MemTotal /proc/meminfo | grep -Po "MemTotal:\s+\K\d+") -lt $MIN_PARALLEL_BUILD_RAM_KB ]]; then
         printf "\nRAM is smaller than 16 GB. Parallel build will be disabled for stability.\n\n"
         export COLCON_EXTRA_ARGS="${COLCON_EXTRA_ARGS} --executor sequential"
     fi