When cross-compiling, you must specify a C cross-compiler for cgo to
use. You can do this by setting the generic CC_FOR_TARGET or the
more specific CC_FOR_${GOOS}_${GOARCH} (for example, CC_FOR_linux_arm)
environment variable when building the toolchain using make.bash,
or you can set the CC environment variable any time you run the go tool.

The CXX_FOR_TARGET, CXX_FOR_${GOOS}_${GOARCH}, and CXX