Incorporate improvements from the the experimental branch testing gdb 7.5.1
against the 4.4 tool chain. The changes are relatively modest, but involved a
a huge number of commits. Rather than a great series of partial cherry-picks,
the changes are incorporated by this manual patch.

2013-03-18  Jeremy Bennett <jeremy.bennett@embecosm.com>

	* build-elf32.sh: Build GDB.
	* build-linux.sh: Ensure we have the right tool chain on the path.
	* build-uclibc.sh: Tidy up commenting.
	* dejagnu/baseboards/arc-linux-generic.exp: Set up sysroot command
	file.
	* dejagnu/ftp-extra.exp (make_relative): Correct typo for prefix.
	(ftp_download): Silently ignore long remote file names.
	* dejagnu/telnet-extra.exp (telnet_close): Correct logic.
	(telnet_exec): Tidy up details of proc.
	(telnet_spawn_open): New proc.
	(telnet_spawn): Rewrite logic of proc.
	* run-uclibc-tests.sh (ARC_GDB_COMMFILE): Create command file for
	GDB tests.