microsoft_pe.ksy - pe_signture
According to [pe documentation](https://msdn.microsoft.com/en-us/library/windows/desktop/ms680547(v=vs.85).aspx#signature__image_only_) at 0x3c we have a pointer to the pe header.

the .ksy file extract this field --> mz_placeholder.header_size.
so before reading the pe_signture (the ksy name for pe header) we should seek to that place.

Moreover, the mz2 field is not mandatory, there are valid pe executable with out that field.

Thanks,
y
