pgsql: Use designated initializers for guc_tables

Use designated initializers for guc_tables

This makes the generating script simpler and the output easier to
read.  In the future, it will make it easier to reorder and rearrange
the underlying C structures.

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

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/0a7bde46101697ece7549df29078ff9417347438

Modified Files
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src/backend/utils/misc/gen_guc_tables.pl | 53 +++++++++++++-------------------
1 file changed, 22 insertions(+), 31 deletions(-)