MINOR: flags/mux-h1: decode H1C and H1S flags

The new functions h1c_show_flags() and h1s_show_flags() decode the flags
state into a string, and are used by dev/flags:

$ /dev/flags/flags h1c 0x2200
h1c->flags = H1C_F_ST_READY | H1C_F_ST_ATTACHED

./dev/flags/flags h1s 0x190
h1s->flags = H1S_F_BODYLESS_RESP | H1S_F_NOT_FIRST | H1S_F_WANT_KAL
2 files changed