StructBox`1 IEquatable
StructBox`1 IEquatable

ref https://github.com/peachpiecompiler/peachpie/issues/912

iolevel/peachpie-concept,peachpiecompiler/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept,peachpiecompiler/peachpie,iolevel/peachpie-concept