* tests/Makefile.am: Add test-redirection-loop to tests
* tests/libtest.c (_http_server_thread): Check scope of requested URL,
skip check for expected files when not specified
* tests/libtest.h: Add wget_test_url_t.scope,
define WGET_TEST_URL_SCOPE_HTTP and WGET_TEST_URL_SCOPE_HTTPS
* tests/test-redirection-loop.c: New test file