Write isColumnFull function

src/main/c/VierGewinnt.c

@@ -133,3 +133,8 @@ void clearScreen() {
     system("clear");
 #endif
 }
+
+// Write isColumnFull function
+int isColumnFull(char board[ROWS][COLS], int col) {
+    return (board[0][col] != ' ');
+}