Makefile fixes.

Makefile

@@ -136,19 +136,18 @@ $(PARSER): $(LEMON_SRC)
 
 .PHONY: libxxhash
 libxxhash:
-	$(MAKE) -C $(XXHASH_DIR) install
+	$(MAKE) -C $(XXHASH_DIR)
 
 
 .PHONY: liblmdb
 liblmdb:
 	$(MAKE) -C $(MDB_DIR)
-	$(MAKE) -C $(MDB_DIR) install
 
 
 install: lib ## Install library and dependencies to $PREFIX. May require sudo.
 	@echo "Installing library files in $(PREFIX)."
-	cd $(MDB_DIR); PREFIX=$(PREFIX) make install
-	cd $(XXHASH_DIR); PREFIX=$(PREFIX) make install
+	PREFIX=$(PREFIX) make -C $(MDB_DIR) install
+	PREFIX=$(PREFIX) make -C $(XXHASH_DIR) install
 	mkdir -p $(DESTDIR)$(libdir)
 	mkdir -p $(DESTDIR)$(includedir)
 	cp liblsuprdf.a liblsuprdf.so $(DESTDIR)$(libdir) && \
@@ -158,7 +157,7 @@ install: lib ## Install library and dependencies to $PREFIX. May require sudo.
 debug_install: install debug ## Install standard and debug libraries.
 	@echo "Installing debug library files in $(PREFIX)."
 	cp liblsuprdf_dbg.a liblsuprdf_dbg.so $(DESTDIR)$(libdir)
-	
+
 
 .PHONY: clean ## Clean up artifacts, including language parsers.
 clean: