Bjorn/compiler/v3 core type fix

Suggested replacement for https://github.com/erlang/otp/pull/300

Extract annotations from filter qualifiers in a type-friendly way
    
    Commit 78ce8917d started to use get_anno/1 to extract the line
    annotation from filter qualifiers in comprehensions, but this does not
    respect the spec of this function and resuls in a dialyzer warning.
    To make the code more type-friendly, introduce a get_qual_anno/1
    function.
    
    Kostis Sagonas suggested that the function should be implemented
    similar to this to also ensure that the qualifiers are of the
    appropriate form:
    
    get_qual_anno({call,Line,_,_}) -> Line;
    get_qual_anno({op,Line,_,_,_}) -> Line;
    .
    .
    .
    get_qual_anno({var,Line,_}) -> Line.
    
    The problem is that it is difficult to know exacly which forms
    that may occur and the function will need to be updated if new
    abstract forms are added. Thus this implementation would complicate
    maintanance without any real payoff.