...like we do for "runtime" functions, so that they fail informatively
if executed. They all need intrinsics, but only some are yet defined.
Also:
- added test for issue 9462
- "BUG" in test output is now a failure in all tests (not just $GOROOT tests)
- added intrinsic for reflect.SliceOf
- show dynamic type of panic value
Fixes issue 9462
Change-Id: I3a504c7faeed81e922fedc7dd59222717f3a7e95
Reviewed-on: https://go-review.googlesource.com/2145
Reviewed-by: Robert Griesemer <gri@golang.org>