fix CVE-2026-61915: double-free in the CalDAV VPATCH BYPARAM selector,
reachable by an authenticated calendar user patching a resource with two or
more properties of the matched kind
do not free VPATCH parameters already removed by reference: the parameter
stays owned by libical after icalproperty_remove_parameter_by_ref(), so the
following icalparameter_free() double-freed it and aborted the CalDAV worker
on any VPATCH carrying a PATCH-ACTION parameter
use strcmpsafe/strncmpsafe for PATCHACTION string matching:
icalparameter_get_xvalue() and icalproperty_get_value_as_string() may return
NULL on the same VPATCH path
disable the cassandane test runner by default: on i686 its noarch perl
dependencies are absent from the i686 mirror of centos8.4-Devel, and on x86_64
the prebuilt imaptest helper dies on SIGBUS (769 run, 0 failures, 64 errors,
all the same crash); the cunit suite continues to run on both architectures