Log Message:
Convert the mplayer* and mencoder* packages to the options framework.
This means that the MPLAYER_ENABLE_RUNTIME_CPU_DETECTION,
MPLAYER_DISABLE_DRIVERS and MPLAYER_USE_MEDIALIB become deprecated
(although still recognized).

Visible changes in the resulting binary packages should be minimum by
default (everything that was enabled before still is, and the same
dependencies are kept).  A notable addition, though, is the support for
user-defined menus, closing PR pkg/29784.

Also note that (almost) all dependencies have now a corresponding option
to disable them in case you want to get a minimalist mplayer package.
'make show-options' is your friend ;)

With thanks to wiz@ and dillo@ for their comments and help.