Check diff for all targets

[kennykerr]

Now that #2402 has been fixed, here's hoping we can enable diff checks for all targets.

[riverar]

So msvc is failing because unbeknownst to me, the linker is embedding its version number into the output. 14.35.32215 becomes 0E 00 | 23 00 | D7 7D. Let me go spelunking in the linker.

[riverar]

Looks like it emits the version string in link.exe!CImplib::EmitImportDescriptor. Doesn't look like it's tied into the existing undocumented /Brepro; that would have been too easy.