This is an attempt to amelioriate the situation found in #2384 where
we see the cURL connect() failing to complete. Based on the pcap
from the bug log, we believe that RISC OS is likely failing to signal
the completion of the connection to cURL. As such, cURL times out.
This change permits retries of timed out connections in the hope that
a fresh socket FD might subsequently function correctly. The defaults
chosen mean that the previous behaviour of 30 seconds before timeout
is reported will remain the same, but in that time we will make 3 separate
attempts to connect the socket.
This changes the LOG macro to be varadic removing the need for all
callsites to have double bracketing and allows for future improvement
on how we use the logging macros.
The callsites were changed with coccinelle and the changes checked by
hand. Compile tested for several frontends but not all.
A formatting annotation has also been added which allows the compiler
to check the parameters and types passed to the logging.
