pgsql: Cosmetic improvements for options-handling code inECPGconnect()

Cosmetic improvements for options-handling code in ECPGconnect().

The comment describing the string format was a lie.  Make it agree with
reality, add/improve some other comments, fix coding style for loops with
empty bodies.  Also add an Assert that we counted parameters correctly,
because the spread-out logic for that looks pretty fragile.

No actual bugs fixed here, so no need to back-patch.

Discussion: https://postgr.es/m/848B1649C8A6274AA527C4472CA11EDD5FC70CBE@G01JPEXMBYT02

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b61a5e6a1f8d4d9e0bfe5d26bebfbb0687353c08

Modified Files
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src/interfaces/ecpg/ecpglib/connect.c | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)