Initialise custom TIFF directory offsets, as some versions of libtiff seem

to only set the low 32 bits of the 64 bit offset if the file only contains
a 32 bit offset.

libs/spandsp/src/t4_tx.c

@@ -620,6 +620,7 @@ static int get_tiff_directory_info(t4_tx_state_t *s)
 
     /* If global parameters are present they should only be on the first page of the file.
        However, as we scan the file we might as well look for them on any page. */
+    diroff = 0;
     if (TIFFGetField(t->tiff_file, TIFFTAG_GLOBALPARAMETERSIFD, &diroff))
     {
         if (!TIFFReadCustomDirectory(t->tiff_file, diroff, &tiff_fx_field_array))