[JuliaSyntax] core_parser_hook returns the last_offset as a UInt32 on 32 bit systems, breaking jl_parse

[xal-0]

@fatteneder encountered this while embedding 32 bit Julia. jl_eval_string ceases to work at all if the JuliaSyntax parser has been enabled, because jl_parse expects the return value of Core._parse to use a C long for the offset:

    JL_TYPECHK(parse, expr, jl_svecref(result, 0));
    JL_TYPECHK(parse, long, jl_svecref(result, 1));

Compare JuliaSyntax.last_byte on x86_64:

julia> Base.infer_return_type(Base.JuliaSyntax.last_byte, (Base.JuliaSyntax.ParseStream,))
Int64

vs x86:

julia> Base.infer_return_type(Base.JuliaSyntax.last_byte, (Base.JuliaSyntax.ParseStream,))
UInt32