Fixed for works correctly in emacs 24.4
Merge branch 'nna774-fix'
Make zlc work correctly under Emacs < 24.4
Fix errors under Emacs 24.3.93

In Emacs 24.3.93,` completion--do-completion' function requires two
arguments as in Emacs 24.4, whereas Emacs 23.3.1 doesn't require
them. To select the proper calling style, we check the function's arity
by using help-function-arglist, instead of checking the version.