eolian: Added eolian_function_is_constructor().

eolian: Added eolian_function_is_constructor().

This patch adds a list of strings called 'ctor_of' to
_Eolian_Function. This list will contain all classes in which this
function is a constructing function.

ctor_of is filled in two moments:

* When filling the constructors of a class, class->full_name is inserted
  in the 'ctor_of' of each constructor's function.

* When filling the implements of a class, if the function is a
  constructor of its superclass it also becomes a constructor of the
  current class, so class->full_name is also inserted in the 'ctor_of'
  of each implement's function.

eolian_function_is_constructor gets a func and klass arguments. It goes
through ctor_of of func and returns EINA_TRUE if klass->full_name is
found, otherwise it returns EINA_FALSE.