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
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/a29e93e8f9da8f9176174901526bca4681b586e1

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                  | 6 +++++-
src/test/ssl/{ServerSetup.pm => t/SSLServer.pm} | 2 +-
8 files changed, 21 insertions(+), 2 deletions(-)