(hopefully) Fix FS#12639 and other skin related buflib corruption issues.

Kudos to funman for figuring out the problem - skin_find_item() rather
stupidly uses the global skin_buffer variable in skin_parser.c which is
fine in the parser EXCEPT it gets changed in skin_render when the sbs
is being redrawn while another skin is loading, so fix this by makeing
skin_find_item() use a local data pointer so a skin_render() during
parsing won't break anything.

Change-Id: I80e1c0efe569c18225e5772159c18ebb21e07332

Conflicts:

	apps/gui/skin_engine/skin_parser.c
2 files changed