Call direct system calls for socket operations

Explicit system calls for the socket operations were added in Linux kernel
in commit 86250b9d12ca for powerpc. This patch make use of those instead of
calling socketcall to save number of cycles on networking syscalls.

2015-08-25  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>

	* sysdeps/unix/sysv/linux/powerpc/kernel-features.h: Define new macros.
	* sysdeps/unix/sysv/linux/accept.c: Call direct system call.
	* sysdeps/unix/sysv/linux/bind.c: Call direct system call.
	* sysdeps/unix/sysv/linux/connect.c: Call direct system call.
	* sysdeps/unix/sysv/linux/getpeername.c: Call direct system call.
	* sysdeps/unix/sysv/linux/getsockname.c: Call direct system call.
	* sysdeps/unix/sysv/linux/getsockopt.c: Call direct system call.
	* sysdeps/unix/sysv/linux/listen.c: Call direct system call.
	* sysdeps/unix/sysv/linux/recv.c: Call direct system call.
	* sysdeps/unix/sysv/linux/recvfrom.c: Call direct system call.
	* sysdeps/unix/sysv/linux/recvmsg.c: Call direct system call.
	* sysdeps/unix/sysv/linux/send.c: Call direct system call.
	* sysdeps/unix/sysv/linux/sendmsg.c: Call direct system call.
	* sysdeps/unix/sysv/linux/sendto.c: Call direct system call.
	* sysdeps/unix/sysv/linux/setsockopt.c: Call direct system call.
	* sysdeps/unix/sysv/linux/shutdown.c: Call direct system call.
	* sysdeps/unix/sysv/linux/socket.c: Call direct system call.
	* sysdeps/unix/sysv/linux/socketpair.c: Call direct system call.