pgsql: Rewrite PageIndexDeleteNoCompact into a form that only deletes 1

Rewrite PageIndexDeleteNoCompact into a form that only deletes 1 tuple.

The full generality of deleting an arbitrary number of tuples is no longer
needed, so let's save some code and cycles by replacing the original coding
with an implementation based on PageIndexTupleDelete.

We can always get back the old code from git if we need it again for new
callers (though I don't care for its willingness to mess with line pointers
it wasn't told to mess with).

Discussion: <552(dot)1473445163(at)sss(dot)pgh(dot)pa(dot)us>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/24992c6db9fd40f342db1f22747ec9e56483796d

Modified Files
--------------
src/backend/access/brin/brin_pageops.c | 2 +-
src/backend/access/brin/brin_xlog.c | 4 +-
src/backend/storage/page/bufpage.c | 194 ++++++++++++---------------------
src/include/storage/bufpage.h | 3 +-
4 files changed, 74 insertions(+), 129 deletions(-)