pgsql: Add --copy-file-range option to pg_upgrade.

Add --copy-file-range option to pg_upgrade.

The copy_file_range() system call is available on at least Linux and
FreeBSD, and asks the kernel to use efficient ways to copy ranges of a
file. Options available to the kernel include sharing block ranges
(similar to --clone mode), and pushing down block copies to the storage
layer.

For automated testing, see PG_TEST_PG_UPGRADE_MODE. (Perhaps in a later
commit we could consider setting this mode for one of the CI targets.)

Reviewed-by: Peter Eisentraut <peter(at)eisentraut(dot)org>
Discussion: https://postgr.es/m/CA%2BhUKGKe7Hb0-UNih8VD5UNZy5-ojxFb3Pr3xSBBL8qj2M2%3DdQ%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d93627bcbe5001750e7611f0e637200e2d81dcff

Modified Files
--------------
configure | 2 +-
configure.ac | 1 +
doc/src/sgml/ref/pgupgrade.sgml | 13 +++++++
meson.build | 1 +
src/bin/pg_upgrade/TESTING | 4 +-
src/bin/pg_upgrade/check.c | 3 ++
src/bin/pg_upgrade/file.c | 78 ++++++++++++++++++++++++++++++++++++++
src/bin/pg_upgrade/option.c | 7 +++-
src/bin/pg_upgrade/pg_upgrade.h | 4 ++
src/bin/pg_upgrade/relfilenumber.c | 8 ++++
src/include/pg_config.h.in | 3 ++
11 files changed, 120 insertions(+), 4 deletions(-)