openal MinGW 编译

VS2109太大了，安装要100多G。同样功能的MinGW gcc编译器+msys，只要几百兆。磁盘空间就是钱啊。遂改用MinGW了。

1，下载 MinGW，msys。

2，下载 openal-soft-1.20.1.tar.bz2 : https://www.openal-soft.org/openal-releases/openal-soft-1.20.1.tar.bz2

3，下载cmake : cmake-3.18.0-win64-x64.msi : https://github.com/Kitware/CMake/releases/download/v3.18.0/cmake-3.18.0-win64-x64.msi

安装：

1，安装cmake

2，安装MinGW，msys

3，解压 openal-soft ，进入源码目录，建立 build 目录(如果没有)，进入 build 目录，执行 cmake .. -G "MinGW Makefiles",生成Makefile。
4，执行mingw32-make，编译

5，编译出错解决：

Stripping ordinals from OpenAL32.def and generating OpenAL32.lib...
/bin/sed: invalid option -- i
Usage: /bin/sed [OPTION]... {script-only-if-no-other-script} [input-file]...

  -n, --quiet, --silent
                 suppress automatic printing of pattern space
  -e script, --expression=script
                 add the script to the commands to be executed
  -f script-file, --file=script-file
                 add the contents of script-file to the commands to be executed
  -c  --nocr     turn off \r$ translation; must be first switch on command line
      --help     display this help and exit
  -V, --version  output version information and exit

If no -e, --expression, -f, or --file option is given, then the first
non-option argument is taken as the sed script to interpret.  All
remaining arguments are names of input files; if no input files are
specified, then the standard input is read.

E-mail bug reports to: [e-mail] .
Be sure to include the word ``sed'' somewhere in the ``Subject:'' field.
mingw32-make[2]: *** [CMakeFiles\OpenAL.dir\build.make:924: OpenAL32.dll] Error 4
mingw32-make[2]: *** Deleting file 'OpenAL32.dll'
mingw32-make[1]: *** [CMakeFiles\Makefile2:152: CMakeFiles/OpenAL.dir/all] Error 2
mingw32-make: *** [Makefile:149: all] Error 2

意思是/bin/sed不识别 -i 选项，出错文件是 CMakeFiles\OpenAL.dir\build.make:924 ，编辑该文件，删除 -i 选项

6，继续执行mingw32-make编译，成功。