Fix handling of Linux systems without struct statfs64

* acinclude.m4 (AC_STATFS64): New macro to check for struct statfs64.
* configure.ac: Call AC_STATFS64.
* file.c (printstatfs64, sys_statfs64, sys_fstatfs64): Compile only
  if struct statfs64 is available.

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
diff --git a/file.c b/file.c
index 14df971..d6a2885 100644
--- a/file.c
+++ b/file.c
@@ -1680,7 +1680,7 @@
 	return 0;
 }
 
-#ifdef LINUX
+#if defined LINUX && defined HAVE_STATFS64
 static void
 printstatfs64(struct tcb *tcp, long addr)
 {