hopefully this should fix the compile error for p3dcert on osx

makepanda/makepanda.py

@@ -3883,6 +3883,7 @@ if (RTDIST or RUNTIME):
       OPTS=['NOSTRIP', 'OPENSSL', 'FLTK', 'WINCOMCTL', 'WINSOCK']
     else:
       OPTS.append("WX")
+      if (sys.platform=="darwin"): OPTS.append("GL")
       TargetAdd('plugin_p3dCert.obj', opts=OPTS, input='p3dCert_wx.cxx')
       TargetAdd('p3dcert.exe', input='plugin_mkdir_complete.obj')
       TargetAdd('p3dcert.exe', input='plugin_p3dCert.obj')