alpha: switch to generic sys_execve()

get rid of sys_execve() wrapper, while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/alpha/include/asm/unistd.h b/arch/alpha/include/asm/unistd.h
index a31a78e..7826e22 100644
--- a/arch/alpha/include/asm/unistd.h
+++ b/arch/alpha/include/asm/unistd.h
@@ -481,6 +481,7 @@
 #define __ARCH_WANT_SYS_OLDUMOUNT
 #define __ARCH_WANT_SYS_SIGPENDING
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
+#define __ARCH_WANT_SYS_EXECVE
 
 /* "Conditional" syscalls.  What we want is