Remove Linux check for fdatasync().

Android lacks an fdatasync() implementation. Upstream sqlite has also removed
this part of the ifdef.

Change-Id: I656f1b67e8e8880308372a90b100fe9b23f96455
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

src/3rdparty/sqlite/sqlite3.c

@@ -27635,7 +27635,7 @@ SQLITE_API int sqlite3_fullsync_count = 0;
 ** If you know that your system does support fdatasync() correctly,
 ** then simply compile with -Dfdatasync=fdatasync
 */
-#if !defined(fdatasync) && !defined(__linux__)
+#if !defined(fdatasync)
 # define fdatasync fsync
 #endif