Mac下使用Matlab2017/2018，执行mex -setup后提示警告：
Warning:
Xcode is installed, but its license has not been accepted.
Run Xcode and accept its license agreement
首先Max中已经安装好了commend-line-tools
然后在Matlab安装目录文件内修改：
打开文件/Applications/MATLAB_R2017a.app/bin/maci64/mexopts/clang++_maci64.xml
和 /Applications/MATLAB_R2017a.app/bin/maci64/mexopts/clang_maci64.xml
搜索Xcode is installed, but its license has not been accepted. Run Xcode and accept its license agreement, 定位到warning提示行，在代码行<cmdReturns name="defaults read com.apple.dt.Xcode IDEXcodeVersionForAgreedToGMLicense"/>之前添加如下代码：
<cmdReturns name="echo 4.3.3"/>
