pgsql: Change config_generic.vartype to be initialized at compile time

Change config_generic.vartype to be initialized at compile time

Previously, this was initialized at run time so that it did not have
to be maintained by hand in guc_tables.c. But since that table is now
generated anyway, we might as well generate this bit as well.

Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/8fdfb91e-60fb-44fa-8df6-f5dea47353c9(at)eisentraut(dot)org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e1a912c86d5205371b043772aa89908f2452cbf0

Modified Files
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src/backend/utils/misc/gen_guc_tables.pl | 1 +
src/backend/utils/misc/guc.c | 28 +---------------------------
src/include/utils/guc_tables.h | 2 +-
3 files changed, 3 insertions(+), 28 deletions(-)