scons: rework the EGL build

The scons equivalent of the previous commit - just fold the almost
identical driver + main Sconscripts.

Cc: Alexander von Gluck IV <kallisti5@unixzen.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Acked-by: Matt Turner <mattst88@gmail.com>

src/SConscript

@@ -32,8 +32,7 @@ if not env['embedded']:
     if env['platform'] not in ('cygwin', 'darwin', 'freebsd', 'haiku', 'windows'):
         SConscript('glx/SConscript')
     if env['platform'] == 'haiku':
-        SConscript('egl/drivers/haiku/SConscript')
-        SConscript('egl/main/SConscript')
+        SConscript('egl/SConscript')
 
     if env['gles']:
         SConscript('mapi/shared-glapi/SConscript')