index: user a better assertion when comparing sizes

This will tell us which numbers we were trying to compare, rather than
just telling us that they're different.

tests/index/tests.c

@@ -103,8 +103,8 @@ void test_index_tests__default_test_index(void)
 		git_index_entry *e = entries[test_entries[i].index];
 
 		cl_assert_equal_s(e->path, test_entries[i].path);
-		cl_assert(e->mtime.seconds == test_entries[i].mtime);
-		cl_assert(e->file_size == test_entries[i].file_size);
+		cl_assert_equal_i(e->mtime.seconds, test_entries[i].mtime);
+		cl_assert_equal_i(e->file_size, test_entries[i].file_size);
    }
 
    git_index_free(index);