Consolidate Linux semctl implementation

This patch consolidates the semctl Linux implementation in only
one default file, sysdeps/unix/sysv/linux/semctl.c.  If tries to use
the direct syscall if it is supported, otherwise will use the old ipc
multiplex mechanism.

The patch also simplify header inclusion and reorganize internal
compat symbol to be built only if old ipc is defined.

Checked on x86_64, i686, powerpc64le, aarch64, and armhf.

	* sysdeps/unix/sysv/linux/alpha/Makefile (sysdeps_routines): Remove
	oldsemctl.
	* sysdeps/unix/sysv/linux/alpha/semctl.c: Remove file.
	* sysdeps/unix/sysv/linux/arm/semctl.c: Likewise.
	* sysdeps/unix/sysv/linux/microblaze/semctl.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/semctl.c: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/semctl.c: Use defaulf
	implementation.
	* sysdeps/unix/sysv/linux/semctl.c (__new_semctl): Use semctl
	syscall if it is defined.
	* sysdeps/unix/sysv/linux/generic/syscalls.list (semctl): Remove.
	* sysdeps/unix/sysv/linux/alpha/syscalls.list (semctl): Likewise.
	* sysdeps/unix/sysv/linux/hppa/syscalls.list (semctl): Likewise.
	* sysdeps/unix/sysv/linux/ia64/syscalls.list (semctl): Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list (semctl):
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/syscalls.list (semctl): Likewise.