stream_smb: disable by default, mark as GPLv3

It seems libsmbclient has been GPLv3 for years. Also, it's certainly not
LGPL (unlike some of its support libs like talloc). Thus, mpv built with
Samba support is GPLv3.

Disable it by default, so we don't have to go through the trouble to
indicate the correct license in our output, and we don't trick people
into distributing stuff under the wrong license.

Copyright

@@ -28,6 +28,9 @@ under mplayer2, and has been removed from mpv.
 
 "v2.1+" in this context means "version 2.1 or later".
 
+Some libraries are GPLv2+ or GPLv3+ only. Building mpv with Samba support makes
+it GPLv3+.
+
 Source files with specific licenses:
 - everything under etc/ is unknown
 - everything under DOCS/man/ is GPLv2+
@@ -243,7 +246,7 @@ LGPL relicensing status:
     stream/stream_mf.c              unknown
     stream/stream_null.c            LGPL
     stream/stream_rar.c             LGPL
-    stream/stream_smb.c             unknown
+    stream/stream_smb.c             will stay GPLv3
     stream/stream_tv.c              will stay GPL
     stream/tv*                      will stay GPL
     sub/*                           LGPL

stream/stream_smb.c

@@ -5,7 +5,7 @@
  *
  * mpv is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
+ * the Free Software Foundation; either version 3 of the License, or
  * (at your option) any later version.
  *
  * mpv is distributed in the hope that it will be useful,

wscript

@@ -288,9 +288,10 @@ iconv support use --disable-iconv.",
                                 'struct statfs fs; fstatfs(0, &fs); fs.f_namelen')
     }, {
         'name': '--libsmbclient',
-        'desc': 'Samba support',
+        'desc': 'Samba support (makes mpv GPLv3)',
         'deps': [ 'libdl' ],
         'func': check_pkg_config('smbclient'),
+        'default': 'disable',
         'module': 'input',
     }, {
         'name' : '--lua',