pgsql: Fix incremental backup interaction with XLOG_DBASE_CREATE_FILE_C

Fix incremental backup interaction with XLOG_DBASE_CREATE_FILE_COPY.

After XLOG_DBASE_CREATE_FILE_COPY, a correct incremental backup needs
to copy in full everything with the database and tablespace OID
mentioned in that record; but that record doesn't specifically mention
the blocks, or even the relfilenumbers, of the affected relations.
As a result, we were failing to copy data that we should have copied.

To fix, enter the DB OID and tablespace OID into the block reference
table with relfilenumber 0 and limit block 0; and treat that as a
limit block of 0 for every relfilenumber whose DB OID and tablespace
OID match.

Also, add a test case.

Patch by me, reviewed by Noah Misch.

Discussion: http://postgr.es/m/CA+Tgmob0xa=ByvGLMdAgkUZyVQE=r4nyYZ_VEa40FCfEDFnTKA@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/d75c4027b6f260f2045b162017567aeeb909b056

Modified Files
--------------
src/backend/backup/basebackup_incremental.c | 18 ++++++-
src/backend/postmaster/walsummarizer.c | 75 ++++++++++++++++++++++++++
src/bin/pg_combinebackup/meson.build | 1 +
src/bin/pg_combinebackup/t/006_db_file_copy.pl | 58 ++++++++++++++++++++
4 files changed, 151 insertions(+), 1 deletion(-)