Rewrite makefiles to explicitly reference DESTDIR to fix bug 3153.

We need this so can not bake DESTDIR into the O'Caml symlinks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97743 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CommandGuide/Makefile b/docs/CommandGuide/Makefile
index 3b65183..2c2d076 100644
--- a/docs/CommandGuide/Makefile
+++ b/docs/CommandGuide/Makefile
@@ -77,9 +77,9 @@
 clean-local::
 	$(Verb) $(RM) -f pod2htm*.*~~ $(HTML) $(MAN) $(PS)
 
-HTML_DIR := $(PROJ_docsdir)/html/CommandGuide
-MAN_DIR  := $(PROJ_mandir)/man1
-PS_DIR   := $(PROJ_docsdir)/ps
+HTML_DIR := $(DESTDIR)$(PROJ_docsdir)/html/CommandGuide
+MAN_DIR  := $(DESTDIR)$(PROJ_mandir)/man1
+PS_DIR   := $(DESTDIR)$(PROJ_docsdir)/ps
 
 install-local:: $(HTML) $(INSTALL_MANS) $(PS)
 	$(Echo) Installing HTML CommandGuide Documentation