Relocate alpha from ports to libc

Also fixed the following whitespace nits to satisfy the push:

sysdeps/alpha/alphaev6/memset.S:142: space before tab in indent.
sysdeps/alpha/configure:1: new blank line at EOF.
sysdeps/alpha/fpu/e_sqrt.c:126: space before tab in indent.
sysdeps/alpha/preconfigure:1: new blank line at EOF.
sysdeps/unix/sysv/linux/alpha/syscalls.list:1: new blank line at EOF.

sysdeps/alpha/nptl/pthreaddef.h

@@ -0,0 +1,37 @@
+/* Copyright (C) 2003-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Default stack size.  */
+#define ARCH_STACK_DEFAULT_SIZE	(4 * 1024 * 1024)
+
+/* Required stack pointer alignment at beginning.  The ABI requires 16.  */
+#define STACK_ALIGN		16
+
+/* Minimal stack size after allocating thread descriptor and guard size.  */
+#define MINIMAL_REST_STACK	4096
+
+/* Alignment requirement for TCB.  */
+#define TCB_ALIGNMENT		16
+
+/* Location of current stack frame.  */
+#define CURRENT_STACK_FRAME	__builtin_frame_address (0)
+
+/* XXX Until we have a better place keep the definitions here.  */
+
+/* While there is no such syscall.  */
+#define __exit_thread_inline(val) \
+  INLINE_SYSCALL (exit, 1, (val))