CLSA-2026-1779378574 dovecot: Fix of 2 CVEs

CVE-2026-42006: lib-imap: fix listcountlimit to actually count open '' instead of close '', preventing an imap-login memory-exhaustion DoS that bypassed the CVE-2026-27857 fix...

CLSA-2026-1779360036 dovecot: Fix of CVE-2026-42006

CVE-2026-42006: fix imap-login listcountlimit to actually limit open '' characters; the previous fix limited closing '' instead, leaving the bracing memory exhaustion vector open...

CLSA-2026-1778882329 dovecot: Fix of CVE-2026-27857

CVE-2026-27857: improve fix by enforcing listcountlimit on '' openlist instead of '' closelist; the previous fix did not actually limit memory growth from many '' characters...