hsdis may not work when it was built with --with-binutils=system

JDK-8277089 introduced the feature to build hsdis with binutils which is provided by the system, however it may not work when it was build with --with-binutils=system.

We can see the following message when the problem happens. I saw it on Ubuntu 20.04.

```
hsdis: bad native mach=architecture not set in Makefile!; please port hsdis to this platform
```

The cause is `-DLIBARCH_$OPENJDK_TARGET_CPU_LEGACY_LIB` is not set in `HSDIS_CFLAGS`. For example, it will be set `LIBARCH_amd64` on AMD64. We should set `LIBARCH_$OPENJDK_TARGET_CPU_LEGACY_LIB` to `HSDIS_CFLAGS` even if the builder uses system binutils.