[gtk+] build: Fix variable name for gtk4-update-icon-cache target

[Emmanuele Bassi <ebassi src gnome org>]

commit 976a4f6b12f7e3a6887e7e44b16aae65dcfce6e1
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Oct 18 15:51:05 2016 +0100

    build: Fix variable name for gtk4-update-icon-cache target

 gtk/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 9c481dc..94f3103 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -1634,7 +1634,7 @@ $(GTK_UPDATE_ICON_CACHE_RC):
 $(GTK_UPDATE_ICON_CACHE_MANIFEST_OBJECT): $(GTK_UPDATE_ICON_CACHE_RC) $(GTK_UPDATE_ICON_CACHE_MANIFEST)
        $(WINDRES) --input $< --output $@ --output-format=coff
 
-gtk_update_icon_cache_LDADD += $(GTK_UPDATE_ICON_CACHE_MANIFEST_OBJECT)
+gtk4_update_icon_cache_LDADD += $(GTK_UPDATE_ICON_CACHE_MANIFEST_OBJECT)
 
 endif