Workaround clone syscall mishandling.

https://bugs.gentoo.org/630704
--- a/sysdeputil.c	2017-09-11 11:38:06.522229630 +0200
+++ b/sysdeputil.c	2017-09-11 11:38:10.422229500 +0200
@@ -67,7 +67,9 @@
 #if defined(__linux__)
   #include <errno.h>
   #include <syscall.h>
-  #define VSF_SYSDEP_HAVE_LINUX_CLONE
+  #ifndef __sparc__
+    #define VSF_SYSDEP_HAVE_LINUX_CLONE
+  #endif
   #include <sched.h>
   #ifndef CLONE_NEWPID
     #define CLONE_NEWPID 0x20000000