libc: fix typo in statvfs

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libc/misc/statfs/internal_statvfs.c

@@ -45,7 +45,7 @@
   buf->__f_unused = 0;
 #endif
   buf->f_namemax = fsbuf.f_namelen;
-  memset (buf->__f_spare, '\0', sizeof(fsbuf.f_spare));
+  memset (buf->__f_spare, '\0', sizeof(buf.__f_spare));
   /* XXX I have no idea how to compute f_favail.  Any idea???  */
   buf->f_favail = buf->f_ffree;