Mechanically remove _IO_ name aliases for types and constants.

Mechanically remove _IO_ name aliases for types and constants.

This patch mechanically removes all remaining uses, and the
definitions, of the following libio name aliases:

 name                         replaced with
 ----                         -------------
 _IO_FILE                     FILE
 _IO_fpos_t                   __fpos_t
 _IO_fpos64_t                 __fpos64_t
 _IO_size_t                   size_t
 _IO_ssize_t                  ssize_t or __ssize_t
 _IO_off_t                    off_t
 _IO_off64_t                  off64_t
 _IO_pid_t                    pid_t
 _IO_uid_t                    uid_t
 _IO_wint_t                   wint_t
 _IO_va_list                  va_list or __gnuc_va_list
 _IO_BUFSIZ                   BUFSIZ
 _IO_cookie_io_functions_t    cookie_io_functions_t
 __io_read_fn                 cookie_read_function_t
 __io_write_fn                cookie_write_function_t
 __io_seek_fn                 cookie_seek_function_t
 __io_close_fn                cookie_close_function_t

I used __fpos_t and __fpos64_t instead of fpos_t and fpos64_t because
the definitions of fpos_t and fpos64_t depend on the largefile mode.
I used __ssize_t and __gnuc_va_list in a handful of headers where
namespace cleanliness might be relevant even though they're
internal-use-only.  In all other cases, I used the public-namespace
name.

There are a tiny handful of places where I left a use of 'struct _IO_FILE'
alone, because it was being used together with 'struct _IO_FILE_plus'
or 'struct _IO_FILE_complete' in the same arithmetic expression.

Because this patch was almost entirely done with search and replace, I
may have introduced indentation botches.  I did proofread the diff,
but I may have missed something.

The ChangeLog below calls out all of the places where this was not a
pure search-and-replace change.

Installed stripped libraries and executables are unchanged by this patch,
except that some assertions in vfscanf.c change line numbers.

	* libio/libio.h (_IO_FILE): Delete; all uses changed to FILE.
	(_IO_fpos_t): Delete; all uses changed to __fpos_t.
	(_IO_fpos64_t): Delete; all uses changed to __fpos64_t.
	(_IO_size_t): Delete; all uses changed to size_t.
	(_IO_ssize_t): Delete; all uses changed to ssize_t or __ssize_t.
	(_IO_off_t): Delete; all uses changed to off_t.
	(_IO_off64_t): Delete; all uses changed to off64_t.
	(_IO_pid_t): Delete; all uses changed to pid_t.
	(_IO_uid_t): Delete; all uses changed to uid_t.
	(_IO_wint_t): Delete; all uses changed to wint_t.
	(_IO_va_list): Delete; all uses changed to va_list or __gnuc_va_list.
	(_IO_BUFSIZ): Delete; all uses changed to BUFSIZ.
	(_IO_cookie_io_functions_t): Delete; all uses changed to
	cookie_io_functions_t.
	(__io_read_fn): Delete; all uses changed to cookie_read_function_t.
	(__io_write_fn): Delete; all uses changed to cookie_write_function_t.
	(__io_seek_fn): Delete; all uses changed to cookie_seek_function_t.
	(__io_close_fn): Delete: all uses changed to cookie_close_function_t.

	* libio/iofopncook.c: Remove unnecessary forward declarations.
	* libio/iolibio.h: Correct outdated commentary.
	* malloc/malloc.c (__malloc_stats): Remove unnecessary casts.
	* stdio-common/fxprintf.c (__fxprintf_nocancel):
	Remove unnecessary casts.
	* stdio-common/getline.c: Use _IO_getdelim directly.
	Don't redefine ssize_t.
	* stdio-common/printf_fp.c, stdio_common/printf_fphex.c
	* stdio-common/printf_size.c: Don't redefine size_t or FILE.
	Remove outdated comments.
	* stdio-common/vfscanf.c: Don't redefine va_list.