xtensa: switch to generic clone()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/xtensa/include/asm/unistd.h b/arch/xtensa/include/asm/unistd.h
index f4e6eaa..e002dbc 100644
--- a/arch/xtensa/include/asm/unistd.h
+++ b/arch/xtensa/include/asm/unistd.h
@@ -2,6 +2,7 @@
 #define _XTENSA_UNISTD_H
 
 #define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_SYS_CLONE
 #include <uapi/asm/unistd.h>
 
 /*