libxbps: make sure to remove pkg metadata file on upgrades with skip-obsoletes.

This fixes the following case:

 - A-1.0_1 is installed and owns bin/foo.
 - A-1.1_1 is in the transaction and depends on B-1.0_1 that owns bin/foo.
 - B-1.0_1 is in the transaction and replaces A<1.1_1.
 - A-1.1_1 in the transaction now has "skip-obsoletes".
 - A is updated to 1.1_1, its metadata file (<pkgname>-files.plist) wasn't removed.

Added two new test cases to verify moving files from/to a dependency.

lib/package_unpack.c

@@ -478,6 +478,7 @@ unpack_archive(struct xbps_handle *xhp,
 		xbps_object_release(obj);
 	}
 	xbps_object_release(pkg_filesd);
+out:
 	/*
 	 * If unpacked pkg has no files, remove its files metadata plist.
 	 */
@@ -486,7 +487,6 @@ unpack_archive(struct xbps_handle *xhp,
 		unlink(buf);
 		free(buf);
 	}
-out:
 	if (xbps_object_type(binpkg_filesd) == XBPS_TYPE_DICTIONARY)
 		xbps_object_release(binpkg_filesd);
 	if (pkgname != NULL)