[gimp] INSTALL: remove --without-libtiff.

[Jehan <jehanp src gnome org>]

commit 2494a06df50aabe649c8f723fb703e101b3231d8
Author: Jehan <jehan girinstud io>
Date:   Sun Oct 31 21:02:59 2021 +0100

    INSTALL: remove --without-libtiff.
    
    It's not optional anymore, for quite some time now.
    Reported in #7450.

 INSTALL.in | 6 ------
 1 file changed, 6 deletions(-)
---
diff --git a/INSTALL.in b/INSTALL.in
index deb96ff7c0..9a9bc30f4c 100644
--- a/INSTALL.in
+++ b/INSTALL.in
@@ -289,12 +289,6 @@ These are:
      how image data is transported between the core and plug-ins. Usually
      the best way to do this is detected automatically.
 
-  --without-libtiff.  configure will bail out if libtiff can not be
-     found. You better fix the underlying problem and install these
-     libraries with their header files. If you absolutely want to
-     compile GIMP without support for TIFF you need to explicitly
-     disable them using this option.
-
   --without-aa.  The AA plug-in needs libaa and configure checks for
      its presence. Use --without-aa if you run into problems.