[meson] move luabins to subprojects

meson.build

@@ -188,7 +188,7 @@ if not deps.contains(luajit)
 else
     luajit_inc = include_directories(luajit.get_pkgconfig_variable('includedir'))
 endif
-subdir('vendor/luabins/src')
+subdir('subprojects/luabins/src')
 
 dep_gl = dependency('gl', required: false)
 if not dep_gl.found()
@@ -202,6 +202,9 @@ if not dep_gl.found()
         dep_gl = dependency('', required: false)
     endif
 endif
+if host_machine.system() == 'darwin'
+    conf.set('HAVE_OPENGL_GL_H', 1)
+endif
 
 if not dep_gl.found()
     error('OpenGL implementation not found')