Avoid to send queries to unrelated nodes in streaming replication mode.

Pgpool-II sends certain queries, such as BEGIN, END and SET commands to
all of DB nodes. However in streaming replication mode, only primary
node and at most one standby node are only concerned (if primacy node
is selected as the load balance node, only 1 node is concerned).

Think about 3 nodes cluster. Node 0 is primary, node 1 and 2 are
standby servers. Node 1 is selected as the load balance node. In this
case no query is needed to be sent to node 2, because DMLs are sent to
node 0 while SELECTs are sent to node 1.

For this purpose pool_setall_node_to_be_sent() is modified to only set
related nodes on the where_to_send node map. See [pgpool-hackers: 464]
for more details.
Fix possible buffer overrun problem and memory leak.

To fix the memory leak problem, now libs/pcp/libpcp.a links
strlcpy.o. For this purpose, libs/pcp/Makefile.am is also modified.
Per Coverity 1111465 and 1111482.
Fix possible buffer overrun.

Replace strcpy() with strlcpy(). Per Coverity report 1111478, 1111480,
1111481.
Add dubug messages for analyzing errors in if_up_cmd
Fix freeing NULL.

free_systemdb_info() should check if the argument is NULL or not.
Per Coverity 1111384.
Do not enable query cache on materialized views.

Per bug #95.
Fix memory leak.

Per Coverity 1111446.
Fix a segmentation fault in parallel mode with system_db_hostname is empty

When system_db_hostname is empty, unix domain socket should be used.
However, the directory containing the socket file was't specified in this
case, and the initialization of system DB connection failed. This caused
segmentation fault, when processing a query to system db.
Fix to output debug messages in processing pgpool.conf with -d option

In previous, debug messages in pool_get_config() ware not output
even when -d option was used.
Fix JDBC exception of prepared statement including now() in replication mode

With JDBC, when a prepared statement is executed more than PreparedThreshold times,
the statement is named and Describe message is sent after Parse. With named statement,
pgpool rewrite now() to parameter at Parse in replication mode. Hence, rewritten query
has additonal parameter than original. However, ParameterDescription message sent to
frontend, which is response of Describe, should include OIDs of the same number os
original query's parameters. Otherwize, JDBC raises ArrayIndexoutOfBoundsException.
Fix backend error of prepared statement including now() via JDBC in replication mode

With JDBC, when a prepared statement is executed more than PreparedThreshold times,
the statement is named, and pgpool rewrites now() to parameter in replication mode.
Hence, rewritten query has additonal parameter, so Bind message also should inclued
additional parameter format codes. However, when the number of original parameter was
one, pgpool didn't handle this. This caused a error like "incorrect binary data format
in bind parameter 2" on backend.
Fix a bug of regression test of JDBC that shows OK even when test fails
Add a test of PrepareThreshold to JDBC regression test
Add description about parallel mode doesn't support PREPARE