Improve process status of extend query

Improve process status of extend query

Previously, pgpool status is incorrect with extend query.
For example, when query is executing, but process status
is idle. This fix can display process status correctly.
If 'Execute' message is received, pgpool display process
status the same as Simple query.

For example:
  user databse SELECT

In addition, fix log_statement bug. Previously, statement
using extend query is not logged by log_statement parameter.
It was improved in this commit.

Other, log_per_node_statement can log query with BIND message.