Before commit b366adcf this function didn't do anything for unhandled
opcodes, but the commit made the else branch disable vectorization
for "the rest" of opcodes. That meant that basic opcodes such as ocAdd,
which didn't get thrown out by the SC_OPCODE_START_BIN_OP block (since they
are in the allowed subset), ended up in the else block and vectorization
got disabled.

Change-Id: I9eb408b601f48b8d7b5022ec85225d92729cd778
Reviewed-on: https://gerrit.libreoffice.org/55362Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>