pgsql: Set log_line_prefix and application name in test drivers

Set log_line_prefix and application name in test drivers

Before pg_regress runs psql, set the application name to the test name.
Similarly, set the application name to the test file name in the TAP
tests.  Also, set a default log_line_prefix that show the application
name, as well as the PID and a time stamp.

That way, the server log output can be correlated to the test input
files, making debugging a bit easier.

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/a4327296df7366ecc657b706a9b5e87aa921311a

Modified Files
--------------
src/test/perl/PostgresNode.pm      | 1 +
src/test/perl/TestLib.pm           | 2 ++
src/test/regress/pg_regress.c      | 1 +
src/test/regress/pg_regress_main.c | 7 +++++++
4 files changed, 11 insertions(+)