pgsql: Remove logical_read_local_xlog_page

Remove logical_read_local_xlog_page

It devolved into a content-less wrapper over read_local_xlog_page, with
nothing to add, plus it's easily confused with walsender's
logical_read_xlog_page. There doesn't seem to be any reason for it to
stay.

src/include/replication/logicalfuncs.h becomes empty, so remove it too.
The prototypes it initially had were absorbed by generated fmgrprotos.h.

Discussion: https://postgr.es/m/20191115214102.GA15616@alvherre.pgsql

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5d0c2d5eba6b58b3c9955ee41c917f7df8b62746

Modified Files
--------------
src/backend/replication/logical/logicalfuncs.c | 11 +----------
src/backend/replication/slotfuncs.c | 6 +++---
src/backend/replication/walsender.c | 3 +--
src/include/replication/logicalfuncs.h | 19 -------------------
4 files changed, 5 insertions(+), 34 deletions(-)