[gimp] plug-ins: get rid of compilation warning.

[Jehan <jehanp src gnome org>]

commit de866d881537a2931197ab4752c0047a5d29f766
Author: Jehan <jehan girinstud io>
Date:   Wed Jun 12 12:54:37 2019 +0200

    plug-ins: get rid of compilation warning.
    
    Note that I am using twice TIFFErrorHandler type. This is because
    TIFFWarningHandler does not exist, despite what the docs says and
    upstream code actually uses twice the same handler type.

 plug-ins/file-tiff/file-tiff-io.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/plug-ins/file-tiff/file-tiff-io.c b/plug-ins/file-tiff/file-tiff-io.c
index 2405a8970e..7f1c16b373 100644
--- a/plug-ins/file-tiff/file-tiff-io.c
+++ b/plug-ins/file-tiff/file-tiff-io.c
@@ -74,8 +74,8 @@ tiff_open (GFile        *file,
            const gchar  *mode,
            GError      **error)
 {
-  TIFFSetWarningHandler (tiff_io_warning);
-  TIFFSetErrorHandler (tiff_io_error);
+  TIFFSetWarningHandler ((TIFFErrorHandler) tiff_io_warning);
+  TIFFSetErrorHandler ((TIFFErrorHandler) tiff_io_error);
 
   tiff_io.file = file;