pgsql: Mark ssl_passphrase_command as GUC_SUPERUSER_ONLY.

Mark ssl_passphrase_command as GUC_SUPERUSER_ONLY.

This commit changes the GUC ssl_passphrase_command so that
it's examinable by only superuser and a member of pg_read_all_settings.
Per discussion, we determined to do this because the parameter may
contain a sensitive informtaion like a passphrase itself.

Author: Insung Moon
Reviewed-by: Keisuke Kuroda
Discussion: https://postgr.es/m/CAEMmqBuHVGayc+QkYKgx3gWSdqwTAQGw+0DYn3WhcX-eNa2ntA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d9249441efc5b4adc5b1a71f3d16538c68e198fc

Modified Files
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src/backend/utils/misc/guc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)