Support newer versions of objdump

Resolved incompatibilities with newer versions of `objdump`. The most significant change seems to be the newly introduced behaviour where `objdump` interprets arbitrary long sequences of `0x66` bytes as `data32` annotations. However, this does not seem to be valid according to the AMD manual nor `gcc`. To allow crosschecking against newer versions, the cross-checking scripts strips out these annotations.

Alternatively, we could extend the validator to output `data32` annotations, but in that case we would have to perform some post-processing as well i.e. strip them or replace them with `.byte 0x66` in the input which is being fed to `gcc` during cross-check.