Function: hack-local-variables-prop-line

Return local variables specified in the -*- line.
Returns an alist of elements (VAR . VAL), where VAR is a variable
and VAL is the specified value. Ignores any specification for
`mode:' and `coding:' (which should have already been handled
by `set-auto-mode' and `set-auto-coding', respectively).
Return nil if the -*- line is malformed.

If MODE-ONLY is non-nil, just returns the symbol specifying the
mode, if there is one, otherwise nil.