This adds support to compile host and target Go as position-independent
executables.

Host Go will have PIE enabled if Go supports PIE on the host platform.

Target Go will have PIE enabled if Go supports PIE on the target
platform and CONFIG_PKG_ASLR_PIE is selected.

Go 1.13 supports PIE for x86 and arm targets; mips support is in
progress[1].

[1]: https://github.com/golang/go/issues/21222#issuecomment-542064462

Signed-off-by: Jeffery To <jeffery.to@gmail.com>