[gimp] Issue #8695: fix GIR build in autotools.

[Jehan <jehanp src gnome org>]

commit 8bbde7db25be9d1b240ea665a9e3c1999b1034c3
Author: Jehan <jehan girinstud io>
Date:   Sun Oct 9 16:09:10 2022 +0200

    Issue #8695: fix GIR build in autotools.
    
    Fixing this error:
    
    > Gimp-3.0.o:(.data.rel+0x430): undefined reference to `gimp_text_layer_get_type' linking of temporary 
binary failed

 libgimp/Makefile.gi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/libgimp/Makefile.gi b/libgimp/Makefile.gi
index 4aff54b105..c5e8b2ad80 100644
--- a/libgimp/Makefile.gi
+++ b/libgimp/Makefile.gi
@@ -173,7 +173,7 @@ libgimp_introspectable = \
        ../libgimp/gimpprogress.c               \
        ../libgimp/gimpsaveprocedure.c          \
        ../libgimp/gimpselection.c              \
-       ../libgimp/gimptextlayer.h              \
+       ../libgimp/gimptextlayer.c              \
        ../libgimp/gimpthumbnailprocedure.c     \
        ../libgimp/gimpvectors.c