Rewrite with hard-coded offsets into the PE file format to discern
if a binary is PE32 or PE32+, and then to determine if it contains
a "CLR Data Directory" entry that looks valid.
Tested with PE32 and PE32+ compiled Mono binaries, PE32 and PE32+ native
binaries, and a random assortment of garbage files.
Former-commit-id: 9e7ac86ec84f653a2f79b87183efd5b0ebda001b
