lib/util_path.c: add some util functions to work with paths

lib/Makefile

@@ -43,7 +43,7 @@ OBJS += transaction_files.o transaction_fetch.o
 OBJS += pubkey2fp.o package_fulldeptree.o
 OBJS += download.o initend.o pkgdb.o
 OBJS += plist.o plist_find.o plist_match.o archive.o
-OBJS += plist_remove.o plist_fetch.o util.o util_hash.o 
+OBJS += plist_remove.o plist_fetch.o util.o util_path.o util_hash.o
 OBJS += repo.o repo_pkgdeps.o repo_sync.o
 OBJS += rpool.o cb_util.o proplib_wrapper.o
 OBJS += package_alternatives.o