but with less precision than hardware counterparts.
fixed a number of tests to output BUG when they failed.
changed the runner to distinghuish between output
and output containing ^BUG
R=rsc
CC=dho, golang-dev
https://golang.org/cl/1778041
* correct symbol table size
* do not reorder functions in output
* traceback
* signal handling
* use same code for go + defer
* handle leaf functions in symbol table
R=kaib, dpx
CC=golang-dev
https://golang.org/cl/884041