Revert "net: in (*netFD).dial, use the passed in local address if getsockname fails"

Revert "net: in (*netFD).dial, use the passed in local address if getsockname fails"

This reverts CL 366536

Reason for revert: may have caused #50033 due to an invalid or partially-populated *TCPAddr

Fixes #50033

Change-Id: Ia29ca4116503dba65d56e89caa46ba1c848d421a
Reviewed-on: https://go-review.googlesource.com/c/go/+/369982
Trust: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>