Automatically check for the fdatasync() function and replace it with fsync()

if not found. (CVS 2739)

FossilOrigin-Name: 385a08afefaf552db221ae8bd30ecc7e7c07ee5b

configure.ac

@@ -116,7 +116,7 @@ AC_INIT(src/sqlite.h.in)
 dnl Put the RCS revision string after AC_INIT so that it will also
 dnl show in in configure.
 # The following RCS revision string applies to configure.in
-# $Revision: 1.17 $
+# $Revision: 1.18 $
 
 #########
 # Programs needed
@@ -607,6 +607,13 @@ AC_SUBST(TARGET_DEBUG)
 #
 AC_CHECK_FUNC(usleep, [TARGET_CFLAGS="$TARGET_CFLAGS -DHAVE_USLEEP=1"])
 
+#--------------------------------------------------------------------
+# Redefine fdatasync as fsync on systems that lack fdatasync
+#--------------------------------------------------------------------
+
+AC_CHECK_FUNC(fdatasync, , AC_DEFINE(fdatasync, fsync))
+
+
 #########
 # Generate the output files.
 #