- applied gofmt to src and misc

Note: This fix improved formatting of src/pkg/math/all_test.go but leads
to a degradation in src/pkg/exp/4s/xs.go. The latter happened to "work"
before accidentally. Fixing the alignment in that case in general will
be a separate CL.

Fixes #628.

R=rsc
CC=golang-dev
https://golang.org/cl/223054