libmicrohttpd: add dependency on file and disable spdy

libmicrohttpd: add dependency on file and disable spdy

* fixes following floating dependencies:
  libmicrohttpd/libmicrohttpd-bin/latest lost dependency on  file
  WARN: libmicrohttpd rdepends on libssl but it isn't a build dependency? [build-deps]

* and unknown-configure-option qa warning:
  libmicrohttpd-0.9.34: libmicrohttpd: configure was passed
    unrecognised options: --enable-gnutls [unknown-configure-option]

(From meta-openembedded rev: 681f89a5e05768d09087b9adf4ce21dee59b36ad)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>