pgsql: Build all Flex files standalone

Build all Flex files standalone

The proposed Meson build system will need a way to ignore certain
generated files in order to coexist with the autoconf build system,
and C files generated by Flex which are #include'd into .y files make
this more difficult. In similar vein to 72b1e3a21, arrange for all Flex
C files to compile to their own .o targets.

Reviewed by Andres Freund

Discussion: https://www.postgresql.org/message-id/20220810171935.7k5zgnjwqzalzmtm%40awork3.anarazel.de
Discussion: https://www.postgresql.org/message-id/CAFBsxsF8Gc2StS3haXofshHCzqNMRXiSxvQEYGwnFsTmsdwNeg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dac048f71ebbcf2f980d280711f8ff8001331c5d

Modified Files
--------------
contrib/cube/.gitignore | 1 +
contrib/cube/Makefile | 16 +++++----
contrib/cube/cube.c | 6 ++--
contrib/cube/cubedata.h | 6 ++--
contrib/cube/cubeparse.y | 6 +---
contrib/cube/cubescan.l | 44 ++++++++++++++---------
contrib/seg/.gitignore | 1 +
contrib/seg/Makefile | 15 +++++---
contrib/seg/segparse.y | 3 --
contrib/seg/segscan.l | 28 +++++++++------
src/backend/Makefile | 7 ++--
src/backend/bootstrap/.gitignore | 1 +
src/backend/bootstrap/Makefile | 11 ++++--
src/backend/bootstrap/bootparse.y | 2 --
src/backend/bootstrap/bootscanner.l | 60 +++++++++++++++++--------------
src/backend/replication/.gitignore | 2 ++
src/backend/replication/Makefile | 22 +++++++++---
src/backend/replication/repl_gram.y | 2 --
src/backend/replication/repl_scanner.l | 31 ++++++++++------
src/backend/replication/syncrep_gram.y | 2 --
src/backend/replication/syncrep_scanner.l | 21 +++++++----
src/backend/utils/adt/.gitignore | 1 +
src/backend/utils/adt/Makefile | 11 ++++--
src/backend/utils/adt/jsonpath_gram.y | 27 +-------------
src/backend/utils/adt/jsonpath_internal.h | 32 +++++++++++++++++
src/backend/utils/adt/jsonpath_scan.l | 29 +++++++++------
src/backend/utils/misc/Makefile | 5 +--
src/backend/utils/misc/guc-file.l | 8 +++--
src/backend/utils/misc/guc.c | 2 --
src/bin/pgbench/.gitignore | 1 +
src/bin/pgbench/Makefile | 13 +++++--
src/bin/pgbench/exprparse.y | 15 --------
src/bin/pgbench/exprscan.l | 12 ++++++-
src/test/isolation/.gitignore | 1 +
src/test/isolation/Makefile | 15 +++++---
src/test/isolation/specparse.y | 2 --
src/test/isolation/specscanner.l | 28 ++++++++++-----
src/tools/pginclude/headerscheck | 8 +++++
38 files changed, 307 insertions(+), 190 deletions(-)