(ITS#8233) config parser accepts lines with unbalanced quotes

[hyc@openldap.org]

Full_Name: Howard Chu
Version: 2.4
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (50.232.101.67)
Submitted by: hyc


We were tripped up by a misbehaving syncrepl consumer, that was always
connecting as plain syncrepl even though it was intended to use delta-sync.

The config had been pasted out of an email and the mail client had turned some
(but not all) ASCII double-quotes into UTF-8 smart quotes. As such, the syncrepl
stanza ended at
   logfilter="xxxxx

and this wasn't flagged as an error because
  1) the config parser doesn't care if double quotes get terminated or not
  2) the syncrepl config parser doesn't look at logfilter if logbase wasn't
configured. The logbase token was swallowed up in the logfilter.

The parser should be fixed to reject lines with unbalanced quotes.