Enhance error logging for failed connect

[michaelortmann]

Found by: https://github.com/michaelortmann/
Patch by: https://github.com/michaelortmann/
Fixes:

One-line summary:
Enhance error logging for failed connect

Additional description (if needed):
Useful to relate log messages to each other and make it very clear what exactly failed
#1755 already enhanced logging, and this PR enhances it further
Propagate getsockopt error to errno error logging

Test cases demonstrating functionality (if applicable):
Before:

.jump localhost
[...]
[00:29:10] Failed connect to localhost (Connection refused ip 127.0.0.1 port 6667 )

.set prefer-ipv6 1

.jump localhost
[...]
[00:29:17] Failed connect to localhost (Connection refused ip ::1 port 6667 )

After:

.jump localhost
[...]
[00:55:29] Failed connect to localhost:6667 (Connection refused ip 127.0.0.1)

.set prefer-ipv6 1

.jump localhost
[...]
[00:55:36] Failed connect to localhost:6667 (Connection refused ip ::1)

Also getsockerrors like ENETUNREACH are properly propagated to error logging:

Before:

.jump unreachable
[...]
[01:07:48] Failed connect to unreachable (Operation now in progress ip 192.168.6.7 port 6667 )

After:

.jump unreachable
[...]
[01:08:29] Failed connect to unreachable:6667 (Network is unreachable ip 192.168.6.7 prefer-ipv6 0)

[vanosg]

Can you deconflict please?