patch 9.1.0687: Makefile may not install desktop files

Problem:  Makefile may not install desktop files
Solution: Check for "$(DESTDIR)$(DATADIR)" instead of just "$DESTDIR",
          which is usually not defined, add uninstall rules for the
          icons and the desktop files

closes: #15528
fixes: #15546

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/Makefile b/src/Makefile
index 2da0c6f..875a0de 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2624,7 +2624,7 @@
 DESKTOPPATH = $(DESTDIR)$(DATADIR)/applications
 KDEPATH = $(HOME)/.kde/share/icons
 install-icons:
-	if test -n "$(DESTDIR)"; then \
+	if test -n "$(DESTDIR)$(DATADIR)"; then \
 		$(MKDIR_P) $(ICON48PATH) $(ICON32PATH) \
 		$(ICON16PATH) $(DESKTOPPATH); \
 	fi
@@ -2845,6 +2845,8 @@
 	-rm -f $(SYS_OPTWIN_FILE)
 	-rm -f $(DEST_COL)/*.vim $(DEST_COL)/README.txt
 	-rm -rf $(DEST_COL)/tools
+	-rm -f $(DESKTOPPATH)/vim.desktop $(DESKTOPPATH)/gvim.desktop
+	-rm -f $(ICON16PATH)/gvim.png $(ICON32PATH)/gvim.png $(ICON48PATH)/gvim.png
 	-rm -rf $(DEST_COL)/lists
 	-rm -f $(DEST_SYN)/shared/*.vim $(DEST_SYN)/shared/README.txt
 	-rm -f $(DEST_SYN)/modula2/opt/*.vim
diff --git a/src/version.c b/src/version.c
index 0aa9683..72cce65 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    687,
+/**/
     686,
 /**/
     685,