Make warning usable earlier

warning will crash if called before the first call to set_width.  This
commit makes the warning usable from the moment gdb_stderr is set up.

gdb/
2014-08-05  Gary Benson  <gbenson@redhat.com>

	* utils.c (vwarning): Protect calls to target_terminal_ours
	and wrap_here.
List of calls to exit
False positives and other rubbish
Space the list
Replace two random error-exit things
Document
Replace another
Documentation
Replace another
Documentation
Documentation