funcs/func_cdr: Handle empty time values when extracting parsed values

When extracting timestamps that are parsed, time stamp values that are not set
(time values of 0.000000) should not actually result in a parsed string. The
value should be skipped, and the result of the CDR function should be an
empty string.

Prior to this patch, the result was fed to the time formatting, which would
result in an output of a date/time in 1969.
........

Merged revisions 407747 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@407748 f38db490-d61c-443f-a65b-d21fe96a405b
timing: Improve performance for most timing implementations.

This change allows timing implementation data to be stored directly
on the timer itself thus removing the requirement for many
implementations to do a container lookup for the same information.

This means that API calls into timing implementations can directly
access the information they need instead of having to find it.

Review: https://reviewboard.asterisk.org/r/3175/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@407749 f38db490-d61c-443f-a65b-d21fe96a405b