fix preprocessor conditional
bug#18080250 : nodejs adapter build fails in 7.4
merge
Fix bug that prevented clean async shutdown
The node-mysql driver by default constructs an Error object in order
to get a stack that includes the user's call to Query. This can be 
a performance bottleneck. 

mysql_service_provider.js
  set the driver property "trace" to false by default

MySQLConnectionPool.js
  use the connection property mysql_trace to initialize the driver property
Improve error reporting while loading mysql node_module
Add conditional guards around udebug log statements.
Add conditional guards around udebug log messages.
Remove the error handling in jscrund_mysqljs backend which duplicates
work performed in the jscrund frontend.
Try to reduce overhead of stats.incr() calls