Added xbps_repository_pkg_replaces() to handle pkg "replaces" in the transaction.

The frontend (in that case xbps-bin(8)) is only responsible to remove
those packages that have the "trans-action" string object set to "remove".

lib/Makefile

@@ -40,8 +40,8 @@ endif
 OBJS = package_configure.o package_config_files.o package_orphans.o
 OBJS += package_remove.o package_remove_obsoletes.o package_state.o
 OBJS += package_unpack.o package_requiredby.o package_register.o
-OBJS += package_purge.o initend.o transaction_dictionary.o
-OBJS += transaction_sortdeps.o
+OBJS += package_purge.o package_replaces.o initend.o
+OBJS += transaction_dictionary.o transaction_sortdeps.o
 OBJS += cmpver.o download.o fexec.o humanize_number.o plist.o
 OBJS += util.o pkgmatch.o mkpath.o
 OBJS += regpkgdb_dictionary.o repository_register.o