use envar for php (PHP)

server/server

@@ -3,6 +3,10 @@
 ACTION=start
 PID_PATH=/tmp/remote_i3wm_ws.pid
 
+if [ -z "$PHP" ]; then
+	PHP=php
+fi
+
 ri3wmws_stop() {
     if [ -f "$PID_PATH" ]; then
         PID=$(cat "$PID_PATH")
@@ -23,7 +27,7 @@ ri3wmws_start() {
     if [ -f "$PID_PATH" ]; then
         printf "Server already started\n"
     else
-        php src/resource/server.php "$REMOTE_I3WM_WS_OPTIONS" &
+        $PHP src/resource/server.php "$REMOTE_I3WM_WS_OPTIONS" &
         PID=$!
 
         printf $PID > "$PID_PATH"