Use AC_CHECK_TYPES to check for struct stat64

* m4/stat.m4: Remove.
* configure.ac (AC_STAT64): Remove.
(AC_CHECK_TYPES): Add struct stat64.
* file.c: Replace HAVE_STAT64 with HAVE_STRUCT_STAT64.
diff --git a/configure.ac b/configure.ac
index 5b0a38f..055b258 100644
--- a/configure.ac
+++ b/configure.ac
@@ -191,7 +191,6 @@
 	struct stat.st_gen,
 	struct stat.st_rdev
 ]))
-AC_STAT64
 AC_STATFS64
 
 AC_TYPE_SIGNAL
@@ -260,6 +259,8 @@
 AC_CHECK_TYPES([struct mmsghdr],,, [#include <sys/socket.h>])
 AC_CHECK_MEMBERS([struct msghdr.msg_control],,, [#include <sys/socket.h>])
 
+AC_CHECK_TYPES([struct stat64],,, [#include <sys/types.h>
+#include <asm/stat.h>])
 AC_CHECK_TYPES([struct __old_kernel_stat],,, [#include <asm/stat.h>])
 
 AC_CHECK_TYPES([struct pt_all_user_regs, struct ia64_fpreg, struct ptrace_peeksiginfo_args],,,