[dev.power64] 6g,9g: formatters for Prog and Addr details

The pretty printers for these make it hard to understand
what's actually in the fields of these structures.  These
"ugly printers" show exactly what's in each field, which can
be useful for understanding and debugging code.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/175780043