KDE: configure packaging of kwin theme

Makefile

@@ -4,6 +4,8 @@ LOGIN_BACKGROUND=kali-contours
 
 build:
 	bin/update-default-backgrounds $(DESKTOP_BACKGROUND) $(LOGIN_BACKGROUND)
+	cmake -B kwin-theme-build -S KDE-themes/kwin5
+	cmake --build kwin-theme-build
 	$(foreach SUBDIR,$(SUBDIRS),$(MAKE) -C $(SUBDIR) build &&) true
 
 clean:
@@ -11,3 +13,4 @@ clean:
 
 install:
 	$(foreach SUBDIR,$(SUBDIRS),$(MAKE) -C $(SUBDIR) install &&) true
+	cmake --install kwin-build