runtime: get rid of other Go->C calls in test exports.

testSchedLocal* tests need to malloc now because their
stack frames are too big to fit on the G0 stack.

LGTM=iant
R=golang-codereviews, iant, khr
CC=golang-codereviews
https://codereview.appspot.com/133660043
runtime: badreflectcall runs on the G stack - convert to Go.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://codereview.appspot.com/136260043