In GLib 2.62, "some-test-executable -l" outputs TAP headers before the
list of tests. Ignore those lines. Otherwise, the assertion immediately
below will fail, leading to test failure with a message like:

    ERROR:../tests/xmlrpc-server-test.c:347:main: 'g_str_has_prefix (tests[i], "/xmlrpc/")' should be TRUE

Signed-off-by: Simon McVittie <smcv@debian.org>