Tidy up gdbserver specific baseboard test config.

2013-02-20  Jeremy Bennett <jeremy.bennett@embecosm.com>

	* dejagnu/baseboards/arc-linux-aa4.exp: Move most gdbserver config
	to arc-linux-generic.exp
	* dejagnu/baseboards/arc-linux-nsim.exp: Likewise.
	* dejagnu/baseboards/arc-linux-generic.exp: Set most gdbserver
	config.