Look over the install rules and adjust where appropriate

These are just minor tweaks to make sure the 'make install' part does
what it is supposed to do.  I also removed some commented code in the
dtmail Makefile related to SunOS, as that is not currently suppoerted
anyway.

cde/programs/dtcm/dtcm/Makefile.am

@@ -46,4 +46,4 @@ dtcm_editor_SOURCES = datefield.c     deskset.c       dssw.c \
 		      reminders.c     rfp.c
 
 install-exec-hook:
-	mkdir -p $(DESTDIR)/var/spool/calendar
+	$(INSTALL) -m 0755 -d $(DESTDIR)/var/spool/calendar