Backport from mysql-trunk to mysql-5.6 and mysql-5.7.

Bug#19894382 SERVER SIDE PREPARED STATEMENTS LEADS TO POTENTIAL
             OFF-BY-SECOND TIMESTAMP ON SLAVE

For temporal type input parameter (as time, timestamp and
datetime) of server side prepared statement, the fractional
second part is ignored while preparing the query string.
Executing such query string at slave is resulting in a time
value difference between master and server.

For server prepared statement, the parameters passed for
execution are parsed and Item_param objects are created for
it. While preparing Item_param for temporal types time,
timestamp and datetime, precision for fractional second part's
(Item_param::decimals) is set to "0" always. Because of which
while preparing query string with param values, fractional second
value is ignored. So execution of such prepared statements uses
correct values but query string formed is incorrect. Hence
difference in temporal type value is observed on usage of query
string.

Fix:
--------
If temporal types time, timestamp and datetime has fractional
second part then setting microseconds (6 digit) precision for
the Item_param.