[patch gdb]: Fix some DOS-path related issues in gdb

[Mark Kettenis]

> Date: Thu, 3 Mar 2011 13:02:11 +0100
> From: Kai Tietz <ktietz70@googlemail.com>
> 
> Hello,
> 
> This patch fixes some issues related to DOS file-system filenames and
> paths. I am not sure, if I
> hit all places, nevertheless I am sure I hit most.
> This patch uses the libiberty functions & macros about
> directory-separator checks, absolute-path checks,
> and the filename-comparision functions.

Please don't inflict the DOS-stupidity on stuff like bsd-kvm.c and
fbsd-nat.c.