This also replaces all the assembly that previously used the AT&T style
with the (in my opinion) superior Intel syntax.

I tried prepending `.att_syntax prefix`, but that did not work...

The pre-index operator ('!') was missing at the end of the stp
instruction.

As a result, the stack pointer wasn't updated after the
store of the 64-bit pair and the stored values were basically lost when
follow on code used the stack for later store ops.