Libucw: Change sh_ prefix to ucw_.

Libucw: Change sh_ prefix to ucw_.

And update all uses across the tree.

Macros:
sh_fdatasync		->	ucw_fdatasync
sh_fstat		->	ucw_fstat
sh_ftruncate		->	ucw_ftruncate
sh_mmap			->	ucw_mmap
sh_open			->	ucw_open
sh_pread		->	ucw_pread
sh_pwrite		->	ucw_pwrite
sh_seek			->	ucw_seek
sh_stat			->	ucw_stat

Functions:
sh_file_size		->	ucw_file_size

File types:
sh_off_t		->	ucw_off_t
sh_sighandler_t		->	ucw_sighandler_t
sh_stat_t		->	ucw_stat_t
sh_time_t		->	ucw_time_t

Internals:
sh_getopt		->	ucw_getopt
sh_getopt_long		->	ucw_getopt_long
sh_getopt_longonly	->	ucw_getopt_longonly
sh_optarg		->	ucw_optarg
sh_opterr		->	ucw_opterr
sh_optind		->	ucw_optind
sh_optopt		->	ucw_optopt
sh_xfree		->	ucw_xfree
sh_xmalloc		->	ucw_xmalloc
sh_xrealloc		->	ucw_xrealloc