Consolidate Linux msgrcv implementation

Consolidate Linux msgrcv implementation

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

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

	* sysdeps/unix/sysv/linux/alpha/syscalls.list (msgctl): Remove.
	* sysdeps/unix/sysv/linux/arm/syscalls.list (msgctl): Likewise.
	* sysdeps/unix/sysv/linux/generic/syscalls.list (msgctl): Likewise.
	* sysdeps/unix/sysv/linux/hppa/syscalls.list (msgctl): Likewise.
	* sysdeps/unix/sysv/linux/ia64/syscalls.list (msgctl): Likewise.
	* sysdeps/unix/sysv/linux/microblaze/syscalls.list (msgctl): Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/syscalls.list (msgctl):
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/syscalls.list (msgctl): Likewise,
	* sysdeps/unix/sysv/linux/mips/mips64/syscalls.list (msgctl):
	Likewise.
	* sysdeps/unix/sysv/linux/msgrcv.c (__libc_msgrcv): Use msgrcv syscall
	if defined.
	* sysdeps/unix/sysv/linux/sparc/sparc64/msgrcv.c: Remove file.