Box64: use fewer threads for low-ram devices

apps/Box64/install-64

@@ -13,7 +13,17 @@ rm -rf ~/box64
 git clone https://github.com/ptitSeb/box64 || error 'Failed to clone box64 repository!'
 cd box64 || error 'Failed to change directory'
 mkdir build; cd build; cmake .. -DRPI4ARM64=1 -DCMAKE_BUILD_TYPE=RelWithDebInfo || error 'Failed to run cmake in "build" directory'
-make -j8 || error 'Failed to compile'
+
+#determine how many threads can run without running out of memory
+if [ $(($(free -bt | tail -1 | awk '{print $2}')-$(free -bt | tail -1 | awk '{print $3}'))) -le 2000000000 ];then
+  #less than 2GB of available ram
+  threads=3
+else
+  #greater than 2GB of available ram
+  threads=5
+fi
+echo "Compiling Box64 with $threads threads..."
+make -j${threads} || error 'Failed to compile'
 sudo make install || error 'Failed to run "sudo make install"'
 
 if ! sudo systemctl restart systemd-binfmt ;then