On some systems the external linker defaults to PIE. On some systems
DT_TEXTREL does not work correctly. When both are true we have a bad
situation: any Go program built with the default buildmode (exe) that
uses external linking will fail to run. Fix this by passing -no-pie to
the external linker, if the option is supported.

Fixes #17847.

Change-Id: I9b5ff97825d8b7f494f96d29c4c04f72b53dbf4e
Reviewed-on: https://go-review.googlesource.com/33106
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>