For the default build.Context, the Package.Goroot flag indicates when a
package was loaded from the standard library. Until now, the loader
used it to enable the typechecker's intrinsics for the "unsafe" package.
This seemed like a good check, but it is troublesome for clients that
use a nonstandard build.Context. For example, if a client defines
nonstandard Context hooks that load all packages, whether standard or
user-defined, from a flat sstable, there is no way for those hooks to
indicate which packages should have this flag set and which not. As a
result the contents of the "unsafe" package directory are treated as Go
source code when they are merely documentation.
Change-Id: Iea0a7cc9877507d73606391293971a28279c4e4b
Reviewed-on: https://go-review.googlesource.com/19188
Reviewed-by: Robert Griesemer <gri@golang.org>
02f1928320