gdbserver: remove support for LynxOS

This port has been unmaintained for years, remove it.

gdbserver/ChangeLog:

	* configure: Re-generate.
	* configure.ac: Remove srv_lynxos test.
	* configure.srv: Remove lynxos cases.
	* lynx-i386-low.cc, lynx-low.cc, lynx-low.h, lynx-ppc-low.c:
	Remove.

Change-Id: I239d1cf1fc7b4c7a174251bc7981707eaba7d972