x/debug: add syntax for getting the value of an arbitrary symbol in the binary.

Putting arbitrary symbol names through the parser won't work in general,
so we add a built-in function lookup("x") which gets the value of the
symbol x.

Change-Id: Ia35163fc93c0fcdf58bdaacefdc5121a61cd3aa1
Reviewed-on: https://go-review.googlesource.com/16855
Reviewed-by: jcd . <jcd@golang.org>
3 files changed