Fixed MHD_pipe_drain_ with emulated pipes
Fixed MHD_pipe_drain_ with emulated pipes

ghaderer/libmicrohttpd,ghaderer/libmicrohttpd,maru/libmicrohttpd-http2,ghaderer/libmicrohttpd,maru/libmicrohttpd-http2,maru/libmicrohttpd-http2