termios: Consolidate struct termios

termios: Consolidate struct termios

This patch consolidates the struct termios definition on its own header
and adds arch-defined ones for ABIs that deviate from generic
implementation. They are:

  - alpha which has a slight different layout than generic one (c_cc
    field is defined prior c_line).

  - sparc and mips which do not have the c_ispeed/c_ospeed fields.

No semantic change is expected, checked on a build against x86_64-linux-gnu,
alpha-linux-gnu, mips64-linux-gnu, and sparc64-linux-gnu.

	* sysdeps/unix/sysv/linux/alpha/bits/termios-struct.h: New file.
	* sysdeps/unix/sysv/linux/bits/termios-struct.h: Likewise.
	* sysdeps/unix/sysv/linux/mips/bits/termios-struct.h: Likewise.
	* sysdeps/unix/sysv/linux/sparc/bits/termios-struct.h: Likewise.
	* sysdeps/unix/sysv/linux/Makefile (sysdep_headers): Add
	termios-struct.h.
	* sysdeps/unix/sysv/linux/bits/termios.h (struct termios): Move to
	termios-struct.h.
	* sysdeps/unix/sysv/linux/alpha/bits/termios.h (struct termios):
	Likewise.
	* sysdeps/unix/sysv/linux/mips/bits/termios.h (struct termios):
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/bits/termios.h (struct termios):
	Likewise.
	* sysdeps/unix/sysv/linux/sparc/bits/termios.h (struct termios):
	Likewise.
	* sysdeps/unix/sysv/linux/kernel_termios.h (_HAVE_C_ISPEED,
	_HAVE_C_OSPEED): Define.
	* sysdeps/unix/sysv/linux/mips/kernel_termios.h (_HAVE_C_ISPEED,
	_HAVE_C_OSPEED): Likewise.
	* sysdeps/unix/sysv/linux/sparc/kernel_termios.h (_HAVE_C_ISPEED,
	_HAVE_C_OSPEED): Likewise.
	* sysdeps/unix/sysv/linux/speed.c [_HAVE_STRUCT_TERMIOS_C_OSPEED]
	(cfsetospeed): Check for define value instead of existence.
	[_HAVE_STRUCT_TERMIOS_C_ISPEED] (cfsetispeed): Likewise.
	* sysdeps/unix/sysv/linux/tcgetattr.c [_HAVE_STRUCT_TERMIOS_C_ISPEED
	&& _HAVE_C_ISPEED] (__tcgetattr): Likewise.
	* sysdeps/unix/sysv/linux/tcsetattr.c [_HAVE_STRUCT_TERMIOS_C_ISPEED
	&& _HAVE_C_ISPEED] (__tcsetattr): Likewise.