env.bash: export CGO_ENABLED so cgo tests run

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5394042

src/env.bash

@@ -96,7 +96,7 @@ set +o noclobber
 
 # Tried to use . <($MAKE ...) here, but it cannot set environment
 # variables in the version of bash that ships with OS X.  Amazing.
-eval $($MAKE --no-print-directory -f Make.inc go-env | egrep 'GOARCH|GOOS|GOHOSTARCH|GOHOSTOS|GO_ENV')
+eval $($MAKE --no-print-directory -f Make.inc go-env | egrep 'GOARCH|GOOS|GOHOSTARCH|GOHOSTOS|GO_ENV|CGO_ENABLED')
 
 # Shell doesn't tell us whether make succeeded,
 # so Make.inc generates a fake variable name.