Fixes the following two warnings:

    examples/client.c:292:0: error: macro "MAX_OUTLEN" is not used [-Werror=unused-macros]
    examples/tiny-nghttpd.c:298:13: error: function declaration isn’t a prototype [-Werror=strict-prototypes]

Caught using cmake as the autoconf check fails due to unused macros
(HAVE_xxx in conftest.c) and a main function without parameters
respectively.