Can't compile Blender 2.8 on Mac 10.14.2

[xueke_pei]

When compile 2.8 branch of blender on macbook pro use command line,report error like this:

    In file included from  
   /Users/kidux/Blenderdev/blender/extern/audaspace/plugins/openal/OpenALReader.cpp:17:
    /Users/kidux/Blenderdev/blender/extern/audaspace/plugins/openal/OpenALReader.h:31:10: fatal error: 
          'alc.h' file not found
    #include <alc.h>
             ^~~~~~~

and stop working.

[xueke_pei]

When the mac buildbot up to work,the compile error gone away too.