Satisfy linker when building unit test.

This test is not testing anything right now, probably needs to
link in more code from libpromises once it does, but for now keep
it simple.
Partial revert of 0a97e68c48 (Special handling of signals for cf-key)

In that commit, the signal handler for SIGPIPE was removed. SIGPIPE
can easily happen when you pipe your input into for example grep, so
we need to restore this. We ignore the signals so any output after the
signal will just go to the void.
examples/container_key_iteration.cf: add a container key iteration example
Be silent by default if peer sends few bytes. Redmine #5919.

So that cf-serverd does not complain when portscanned,
e.g. selectservers() policy function.
Merge pull request #1743 from jimis/master

Be silent by default if peer sends few bytes. Redmine #5919.
Lower the time spent scanning lastseen DB.

The total DB access time will thus not depend on the time spent running the callback (it seems to be huge in the case of reverse DNS resolution).

This commit makes it easier to later convert the scan into an RDONLY operation.
Merge pull request #1744 from jeffali/fix/scankeys

Lower the time spent scanning lastseen DB.
cf-key -s has its special sig handler but the other operations need one too
Merge pull request #1745 from jeffali/cf_key/generic_sig

cf-key -s has its special sig handler but the other operations need one too
Update changelog
Merge pull request #1746 from maciejmrowiec/master

Update changelog
Redmine#6063: add 0-9 A-Z _ to allowed context of module protocol
replace tab by spaces
Merge pull request #1747 from basvandervlies/fix_changelog_tab

replace tab by spaces
Redmine #4730: Add findfiles support for Windows by glob() replacement
Move several low level file functions to libutils.

This was they can be used from libcompat replacement functions.
Fix misspell in change log.
Revert "Redmine#6063: add 0-9 A-Z _ to allowed context of module protocol"

This reverts commit ec62d6798ede560f496f9073c6d82ff72b1ec3cb.
Merge pull request #1749 from maciejmrowiec/master

Fix misspell in change log.
Revert "Revert "Redmine#6063: add 0-9 A-Z _ to allowed context of module protocol""

This reverts commit 09e23322db65e315834e3c13a82f31bc977fb2e7.