Must take cint lock before calling TCint::CallFunc_Factory

Helgrind found that TCint::CallFunc_Factory indirectly updates
global cint state. Therefore one must take the cint lock before
calling the function. This was the only place (other than
TSelectorCint::Build) which calls this function without first
taking the lock.
Merge pull request #37 from Dr15Jones/lockTCintCallFunc_Factory_calls

Must take cint lock before calling TCint::CallFunc_Factory