cf-serverd: free getaddrinfo() result, on error of OpenReceiverChannel()

getaddrinfo() may allocate the 'result' struct even in cases where it
will return an error. Take care to free memory, although we would exit
the server process anyway.
cf-serverd: getaddrinfo() will use a numeric port, no lookup

This `AI_NUMERICSERV` flag avoids looking up the "services" table for
a string port resolution, according to the manual.
cf-serverd: getaddrinfo() will NOT set "errno" upon failure

It has its own `gai_strerror()` function to resolve its (reentrant)
result code.
Add acceptance test for list extending itself
cf-serverd: fix typo for addrinfo constant

As spotted by Dimitrios Apostolou
Width given in format string is larger than the destination buffer.
Type mismatch between scanf format specifier (unsigned long long) and the variable type (long long).
str*cpy / strlen performance fix.

Calculating length of a string two times is unnecessary, and using strncpy width known string length can be replaced with memcpy.
Variable type fix for fgetc.

Reading a single character is fine with fgetc. But if you want to check for EOF, then you have to use 'int' as type,
and if the return value is not EOF, then it can be cast to 'char'.

Example for fail scenario before the fix: if the file contains 0xff character, then the code will interpret it as EOF.
0xff can be banned, but this should be checked in a proper way and not in the reading code.
Preventing use-after-freed possibility.

Probably the original intention was to prevent the possibility of a use-after-freed bug.
But the last strs = NULL statement has no effect, because it's just a local copy.
However, it makes sense to put a similar solution inside the loop right after the memory release.
This way if some codes try to use a previously freed array, then the array will seem to be empty.
String lib performance fix: using memcpy when the length is known.

Using strncpy(target, string, strlen(string)) equals with memcpy(target, string, strlen(string).
Both of them remove the \0 from the end. But for longer string memcpy is definitely more efficient,
because it does not have to search for string termination.

Usually the performance difference is small, and this kind of code rarely used elsewhere,
but a string handling lib should be efficient.
Type fix: 'char*' should be used for string storing instead of 'char'.
Fix for an unlikely memory leak in a unit test.

1 or 2 hosts work fine, otherwise the reserved memory should be released.
(However, using not 1 or 2 is quite hypothetical.)
strncpy fixes: wrong buffer size, lack of termination and similar errors are fixed.

There are lot of fixes here, but they are in a few main category:
1, strncpy(target, source, TARGETSIZE-1)  -> strlcpy(target, source, TARGETSIZE)
   If the target's last byte is not \0, then the string will not be terminated.
2, strncpy(target, source, TARGETSIZE) -> strlcpy(target, source, TARGETSIZE)
   If the source is longer than the target, then the string will not get NUL termination
3, combination of memset + strncpy or strncpy + buffer[last_byte]=0 -> strlcpy
   It's ugly and inefficient but at least gives correct result.

Remark: the usual string length (e.g. variable name, path) is much shorter than the buffer size (1k or 4k)
Using strncpy is quite inefficient because it always fills the rest of the array with 0s.
If you definitely need this feature, then rather use a memset + strlcpy + comment.
(E.g. // I want to fill this whole buffer with 0s, because it contained a private key previously.)
strncpy / strncat inefficiencies.

strncpy with known length can be replace with memcpy.
manual \0 + strncat is ugly, and strlcpy just does the job well.
strncpy + manual termination -> strlcpy
A few more strncpy fixes: buffer size limit, termination, etc.
Memory leak fix in 'ConfigurationDestroy'.
Correct vzps usage
libpromises/evalfunction.c: let mergedata() use VarRefValueToJson
Change log level for template rendering to INFO.

The promise is recorded as repaired, which uses INFO log level.

Redmine #5214