termios: Consolidate control mode definitions

This patch consolidates the termios symbolic constants used for output
mode with c_cflag memver on its own header.  The Linux generic
implementation values match the kernel UAPI and each architecture with
deviate values have their own implementation (in this case alpha and
powerpc).

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/Makefile (sysdep_headers): Add
	termios-c_cflag.h.
	* sysdeps/unix/sysv/linux/bits/termios-c_cflag.h: New file.
	* sysdeps/unix/sysv/linux/alpha/bits/termios-c_cflag.h: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/bits/termios-c_cflag.h: Likewise.
	* sysdeps/unix/sysv/linux/bits/termios.h (CSIZE, CS5, CS6, CS7, CS8,
	CSTOPB, CREAD, PARENB, PARODD, HUPCL, CLOCAL): Move to
	termios-c_cflag.h.
	* sysdeps/unix/sysv/linux/alpha/bits/termios.h: Likewise.
	* sysdeps/unix/sysv/linux/mips/bits/termios.h: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/bits/termios.h: Likewise.
	* sysdeps/unix/sysv/linux/sparc/bits/termios.h: Likewise.