Create $(TOP)/$(LIB_DIR) for install, too

If `make install' is run without running `make' first, the $(LIB_DIR)
will not be created. This also changes the mkdir a little bit so that it
isn't run if necessary and added `-p' so that it is immune to races.

src/Makefile

@@ -21,7 +21,7 @@ subdirs:
 		fi \
 	done
 
-install:
+install: $(TOP)/$(LIB_DIR)
 	@for dir in $(SUBDIRS) ; do \
 		if [ -d $$dir ] ; then \
 			(cd $$dir && $(MAKE) install) || exit 1 ; \
@@ -29,7 +29,7 @@ install:
 	done
 
 $(TOP)/$(LIB_DIR):
-	-mkdir $(TOP)/$(LIB_DIR)
+	-@test -d $(TOP)/$(LIB_DIR) || mkdir -p $(TOP)/$(LIB_DIR)
 
 
 clean: