cmd/compile: include all entries in map literal hint size

Currently we only include static entries in the hint for sizing
the map when allocating a map for a map literal. Change that to
include all entries.

This will be an overallocation if the dynamic entries in the map have
equal keys, but equal keys in map literals are rare, and at worst we
waste a bit of space.

Fixes #43020

Change-Id: I232f82f15316bdf4ea6d657d25a0b094b77884ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/383634


Run-TryBot: Keith Randall <khr@golang.org>
Trust: Keith Randall <khr@golang.org>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>