Fixed unclean prototype declaration. According to ISO/IEC 9899:TC2:
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10. The special case of an unnamed parameter of type void as the only item in
    the list specifies that the function has no parameters.
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14. An identifier list declares only the identifiers of the parameters of the
    function. An empty list in a function declarator that is part of a
    definition of that function specifies that the function has no parameters.
    The empty list in a function declarator that is not part of a definition of
    that function specifies that no information about the number or types of the
    parameters is supplied. 124)
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6.11.6 Function declarators

The use of function declarators with empty parentheses (not prototype-format
parameter type declarators) is an obsolescent feature.
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Patch contributed by Michal Hrusecky.