[RFA] Remove Java support

[Eli Zaretskii]

> From: Tom Tromey <tom@tromey.com>
> Cc: Tom Tromey <tom@tromey.com>
> Date: Wed,  5 Oct 2016 08:51:22 -0600
> 
> This patch removes the Java support from gdb.  gcj has not seen much
> development or use for years now, and was recently removed from GCC.
> This patch changes gdb to follow; in the unlikely event that there are
> still users using gcj, they can continue to use an older gdb to debug.
> Or, they can debug in C++ mode.

OK for the documentation parts.

Thanks.