pgsql: Fix searchpath and module location for pg_rewind and ssl TAPtes

Fix searchpath and module location for pg_rewind and ssl TAP tests

The modules RewindTest.pm and ServerSetup.pm are really only useful for
TAP tests, so they really belong in the TAP test directories. In
addition, ServerSetup.pm is renamed to SSLServer.pm.

The test scripts have their own directories added to the search path so
that the relocated modules will be found, regardless of where the tests
are run from, even on modern perl where "." is no longer in the
searchpath.

Discussion: https://postgr.es/m/e4b0f366-269c-73c3-9c90-d9cb0f4db1f9@2ndQuadrant.com

Backpatch as appropriate to 9.5

Branch
------
REL_11_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/8722d2cbc0500b8ae1ebaf0a388115617615c1eb

Modified Files
--------------
src/bin/pg_rewind/t/001_basic.pl                | 3 +++
src/bin/pg_rewind/t/002_databases.pl            | 3 +++
src/bin/pg_rewind/t/003_extrafiles.pl           | 3 +++
src/bin/pg_rewind/t/004_pg_xlog_symlink.pl      | 3 +++
src/bin/pg_rewind/t/005_same_timeline.pl        | 3 +++
src/bin/pg_rewind/{ => t}/RewindTest.pm         | 0
src/test/ssl/t/001_ssltests.pl                  | 7 ++++++-
src/test/ssl/t/002_scram.pl                     | 7 ++++++-
src/test/ssl/{ServerSetup.pm => t/SSLServer.pm} | 2 +-
9 files changed, 28 insertions(+), 3 deletions(-)