This does not change anything substantial; it merely simplifies
hypothetical merges back to glibc.
* lib/getopt.c, lib/getopt.in.h, lib/getopt1.c, lib/getopt_int.h:
Change copyright notice to match what is in glibc.
* lib/getopt.c: Reorder includes to match glibc. Remove uses of
USE_IN_LIBIO. Remove 'register'. In __LIBC code, use
__open_memstream rather than open_memstream and __glibc_likely
instead of __builtin_expect.
* lib/getopt.in.h (__posix_getopt) [!__GETOPT_PREFIX]: New decl.