go_1.14: don't set -buildmode=pie when building for windows targets

go 1.14 for windows targets does not support -buildmode=pie, disable it and use
the default buildmode instead. Support for -buildmode=pie for windows targets
is added with go 1.15 (https://golang.org/doc/go1.15

) which is added to poky in
gatesgarth.

Signed-off-by: Peter Morrow <pemorrow@linux.microsoft.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>