BUG/MINOR: contrib/prometheus-exporter: Don't use channel_htx_recv_max()

The function htx_free_data_space() must be used intead. Otherwise, if there are
some output data not already forwarded, the maximum amount of data that may be
inserted into the buffer may be greater than what we can really insert.

This patch must be backported to 2.0.
1 file changed