Update libshout to 2.4.1.

Set LICENSE. Fix installed pkg-config file. Remove unnecessary includes
from bl3.mk. Enable speex support.

libshout 2.4.1 (20151120)

* Fixed issue with missing file in distribution

libshout 2.4.0 (20151111)

* Audio only WebM support.
* Protocol level meta data support improved.
  Some API calls got replaced and marked as obsolete.
* Code hardened.
* Fixed overlinking.
* Removed Debian packaging.
* TLS support (RFC2818 and RFC2817, mode can be autodetected).
* Improved HTTP protocol:
  * Set Host:-header (vhosting),
  * Check for server capabilities.
* Basic support for RoarAudio protocol.

(wiz)