BUILD: proxy: Missing header inclusion for quic_transport_params_init()

Since this commit:
144289b45 ("REORG: move init_default_instance() to proxy.c and pass it the defproxy pointer")
as quic_transport_params_init() has been moved from cfgparse.c to proxy.c this
latter source file must include xprt_quic.h header.

Should fix #1153 issue.
1 file changed