cmd/compile: remove broken rules

cmd/compile: remove broken rules

These rules don't even type check.  ADDQconstmodify returns memory,
and it is being rewritten to a value that returns an int64.

There should be a MOVQstore wrapped around the result.
These rules never fire during all.bash, so they aren't even tested.

I'm just going to remove them for now.

Change-Id: I76008eb51ae4e16c707fac73c05a8d67cac149ae
Reviewed-on: https://go-review.googlesource.com/121935
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>