Fix wrong identifier on .end directive. The SYSCALL macro does name

mangling and creates an .ent directive with the mangled name.

lib/libc/alpha/sys/Ovfork.S

@@ -35,4 +35,4 @@ __FBSDID("$FreeBSD$");
 SYSCALL(vfork)
 	cmovne	a4, zero, v0		/* a4 (rv[1]) != 0, child */
 	RET
-END(vfork)
+END(__sys_vfork)

lib/libc/alpha/sys/fork.S

@@ -35,4 +35,4 @@ __FBSDID("$FreeBSD$");
 SYSCALL(fork)
 	cmovne	a4, zero, v0		/* a4 (rv[1]) != 0, child */
 	RET
-END(fork)
+END(__sys_fork)

lib/libc/alpha/sys/pipe.S

@@ -37,4 +37,4 @@ SYSCALL(pipe)
 	stl	a4, 4(a0)
 	mov	zero, v0
 	RET
-END(pipe)
+END(__sys_pipe)

lib/libc/alpha/sys/setlogin.S

@@ -37,4 +37,4 @@ IMPORT(_logname_valid, 4)			/* in _getlogin() */
 SYSCALL(setlogin)
 	stl	zero, _logname_valid		/* clear it */
 	RET
-END(setlogin)
+END(__sys_setlogin)