pgsql: Rename OverrideSearchPath to SearchPathMatcher.

Rename OverrideSearchPath to SearchPathMatcher.

The previous commit removed the "override" APIs.  Surviving APIs facilitate
plancache.c to snapshot search_path and test whether the current value equals
a remembered snapshot.

Aleksander Alekseev.  Reported by Alexander Lakhin and Noah Misch.

Discussion: https://postgr.es/m/8ffb4650-52c4-6a81-38fc-8f99be981130@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d3a38318ac614f20a9e2e163bba083d15be54f06

Modified Files
--------------
src/backend/catalog/namespace.c     | 24 ++++++++++++------------
src/backend/utils/cache/plancache.c | 12 ++++++------
src/include/catalog/namespace.h     | 12 ++++++------
src/include/utils/plancache.h       |  2 +-
src/tools/pgindent/typedefs.list    |  2 +-
5 files changed, 26 insertions(+), 26 deletions(-)