cscope: match against [[:word:]] not [[:alnum:]]
cscope: match against [[:word:]] not [[:alnum:]]

The intent was good in 528db2849605 but [[:word:]] is the better class; with
[[:alnum:]] we end up making cscope barf with lines like
    with_new = MyClass.new
since we split the variable on its underscore

melong007/starscope,guilherme/starscope,eapache/starscope