scripts/CKC: don't output from shopt
shopt outputs the status of the flag, so that git grep looks like:
git grep -qi 'nocasematch off
^References:.*bsc#1202195' remotes/origin/SLE15-SP2-RT -- 'patches.*'
I don't know how it can work (it does -- maybe thanks to ^), but it's
not definitely OK.
So make shopt in term2regex() quiet.