e4defrag: choose the best available posix_fadvise variant

Use posix_fadvise64() when available.  This allows 64bit offsets on
32bit systems.

[ Modified by tytso to try to use fadvise64() as well, and to remove
  the attempt to call the syscall directly, since because and
  complexities caused by required dummy arguments on some
  architectures, it's not worth the hair.  ]

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/configure.in b/configure.in
index b70a3f9..214d3f6 100644
--- a/configure.in
+++ b/configure.in
@@ -1026,6 +1026,7 @@
 	backtrace
 	blkid_probe_get_topology
 	chflags
+	fadvise64
 	fallocate
 	fallocate64
 	fchown
@@ -1050,6 +1051,7 @@
 	open64
 	pathconf
 	posix_fadvise
+	posix_fadvise64
 	posix_memalign
 	prctl
 	secure_getenv