Replaced redundant dependency sorting code with a simpler implementation.

This fixes the issue found by "xbps-src bootstrap" when a package
without "provides" was declared as a virtual package.

lib/Makefile

@@ -38,7 +38,7 @@ OBJS += package_remove.o package_find_obsoletes.o package_state.o
 OBJS += package_unpack.o package_register.o package_script.o verifysig.o
 OBJS += package_msg.o pkgdb_conversion.o transaction_shlibs.o
 OBJS += transaction_commit.o transaction_package_replace.o
-OBJS += transaction_dictionary.o transaction_sortdeps.o transaction_ops.o
+OBJS += transaction_dictionary.o transaction_ops.o
 OBJS += transaction_revdeps.o pubkey2fp.o
 OBJS += download.o initend.o pkgdb.o package_conflicts.o
 OBJS += plist.o plist_find.o plist_match.o archive.o