Consolidate Linux creat implementation

Consolidate Linux creat implementation

This patch consolidates the creat Linux syscall implementation on
sysdeps/unix/sysv/linux/creat{64}.c.  The changes are:

  1. Remove creat{64} from auto-generation syscalls.list.
  2. Add a new creat{64}.c implementation.  For architectures that
     define __OFF_T_MATCHES_OFF64_T the default creat64 will create
     alias to required creat symbols.
  3. Use __NR_creat where possible, otherwise use internal open{64}
     call with expected flags.

Checked on i686-linux-gnu, x86_64-linux-gnu, x86_64-linux-gnux32,
arch64-linux-gnu, arm-linux-gnueabihf, and powerpc64le-linux-gnu.

	* io/Makefile (CFLAGS-creat.c): New rule.
	(CFLAGS-creat64.c): Likewise.
	* sysdeps/unix/sysv/linux/alpha/creat.c: Remove file.
	* sysdeps/unix/sysv/linux/generic/creat.c: Likewise.
	* sysdeps/unix/sysv/linux/wordsize-64/creat64.c: Likewise.
	* sysdeps/unix/sysv/linux/creat.c: New file.
	* sysdeps/unix/sysv/linux/creat64.c: Likewise.
	* sysdeps/unix/sysv/linux/syscalls.list: Remove create from
	auto-generated list.
	* sysdeps/unix/sysv/linux/wordsize-64/syscalls.list: Likewise.