Emulator: add binary AARCH64 build of X64 PE/COFF emulator

Add a binary RELEASE build targeting AARCH64 systems, created with
Ubuntu's gcc 7.3.0 using the GCC5 profile. This permits such systems
to dispatch and execute option ROMs and other drivers built for the
X64 architecture.

Repo:   http://github.com/ardbiesheuvel/X86EmulatorPkg.git
Commit: 5f4deb30eb935f9004b93d97712cc3ac3ae1ca97

Repo:   http://github.com/tiancore/edk2.git
Commit: 2e21e8c4b89656897797019a9c56bc5ccbf12df1

Note that the X86EmulatorPkg project's license is _L_GPL not GPL,
and so it could arguably be incorporated into edk2-non-osi in source
form. However, the emulator is a rather sizable chunk of code, and
providing a known working binary is preferred over having each
platform build it from scratch, so providing just the binary should
be sufficient for the time being.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>