scripts/gdb: Perform path expansion to lx-symbol's arguments

Python doesn't do automatic expansion of paths.  In case one passes path
of the from ~/foo/bar the gdb scripts won't automatically expand that
and as a result the symbols files won't be loaded.

Fix this by explicitly expanding all paths which begin with "~"

Link: http://lkml.kernel.org/r/1467127337-11135-5-git-send-email-kieran@bingham.xyz


Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Signed-off-by: Kieran Bingham <kieran@bingham.xyz>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>