The internal architecture name of golang is "arm" or "arm64", which has
different naming conventions from netbsd's machine[] or machine_arch[]
("earmv7", "aarch64", etc.) and cannot be used as is.
Instead, use define LINUX_GO_RT0_SIGNATURE_ARCH{32,64}.

- LINUX_GO_RT0_SIGNATURE for compat_linux is no longer enabled by default.
it is now defined in each arch same as the other *_SIGNATURE definitions.
- add new LINUX32_GO_RT0_SIGNATURE for compat_linux32, and is defined in amd64 and aarch64.

add support COMPAT_LINUX for aarch64

add support COMPAT_LINUX for aarch64