给你一个 m x n 的矩阵 board ，由若干字符 'X' 和 'O' 组成，捕获 所有 被围绕的区域：
m x n
board
'X'
'O'
通过 原地 将输入矩阵中的所有 'O' 替换为 'X' 来 捕获被围绕的区域。你不需要返回任何值。
示例 1：
输入：board = [["X","X","X","X"],["X","O","O","X"],["X","X","O","X"],["X","O","X","X"]]
输出：[["X","X","X","X"],["X","X","X","X"],["X","X","X","X"],["X","O","X","X"]]
解释：
在上图中，底部的区域没有被捕获，因为它在 board 的边缘并且不能被围绕。
示例 2：
输入：board = [["X"]]
输出：[["X"]]
提示：
m == board.length
n == board[i].length
1 <= m, n <= 200
board[i][j]
