bug#15591: [PATCH] libparted: handle i18n gpt partition names correctly

gpt.c was simply truncating the UTF-16 characters stored
in the partition name field to 8 bits.  This corrupted non
ascii characters which later resulted in parted crashing in
strlist.c trying to convert the now invalid multi byte
characters to wchar.

gpt.c will now properly convert the UTF-16 to the current
locale encoding.