[gimp] devel-docs: remove gtkbuilder-porting-guide.txt from EXTRA_DIST.

[Jehan <jehanp src gnome org>]

commit 952c24e81b59f7043e1d80b4ba67eee1f35d283e
Author: Jehan <jehan girinstud io>
Date:   Mon Nov 15 16:04:19 2021 +0100

    devel-docs: remove gtkbuilder-porting-guide.txt from EXTRA_DIST.

 devel-docs/Makefile.am | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/devel-docs/Makefile.am b/devel-docs/Makefile.am
index c29ea14d49..8062d27456 100644
--- a/devel-docs/Makefile.am
+++ b/devel-docs/Makefile.am
@@ -34,7 +34,6 @@ EXTRA_DIST = \
        libtool-instructions.txt        \
        parasites.txt                   \
        pat.txt                         \
-       gtkbuilder-porting-guide.txt    \
        release-howto.txt               \
        structure.xml                   \
        submitting-patches.txt          \