[gimp] app: make welcome-dialog-data.[ch] deps relative to $(top_srcdir).

[Jehan <jehanp src gnome org>]

commit eb871a12e730329ec9e13ebde00838e52d447faa
Author: Jehan <jehan girinstud io>
Date:   Sun Mar 6 11:53:14 2022 +0100

    app: make welcome-dialog-data.[ch] deps relative to $(top_srcdir).
    
    Hopefully it will fix the following CI errors:
    
    > make[4]: *** No rule to make target '../../tools/generate-welcome-dialog-data.py', needed by 
'welcome-dialog-data.h'.  Stop.
    
    I thought using relative paths was fine too here, but I might have been
    wrong (even though it worked locally).

 app/dialogs/Makefile.am | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/app/dialogs/Makefile.am b/app/dialogs/Makefile.am
index aa8ea3829f..5b5d470428 100644
--- a/app/dialogs/Makefile.am
+++ b/app/dialogs/Makefile.am
@@ -131,8 +131,8 @@ endif
 
 $(srcdir)/welcome-dialog.c: welcome-dialog-data.h welcome-dialog-data.c
 
-welcome-dialog-data.h: ../../desktop/org.gimp.GIMP.appdata.xml.in.in 
../../tools/generate-welcome-dialog-data.py
+welcome-dialog-data.h: $(top_srcdir)/desktop/org.gimp.GIMP.appdata.xml.in.in 
$(top_srcdir)/tools/generate-welcome-dialog-data.py
        $(top_srcdir)/tools/generate-welcome-dialog-data.py --header $(GIMP_VERSION) > $@
 
-welcome-dialog-data.c: ../../desktop/org.gimp.GIMP.appdata.xml.in.in 
../../tools/generate-welcome-dialog-data.py
+welcome-dialog-data.c: $(top_srcdir)/desktop/org.gimp.GIMP.appdata.xml.in.in 
$(top_srcdir)/tools/generate-welcome-dialog-data.py
        $(top_srcdir)/tools/generate-welcome-dialog-data.py $(GIMP_VERSION) > $@