emulator: Special case x86_64 emulation engine.

As a special case, if the target AVD CPU is 'x86_64', the
'emulator' launcher program will first try to locate a backend
named 'emulator-x86_64', and if not available, will try to find
'emulator-x86' as a fallback.

Other target CPU architectures are not affected.

The main goal here is to experiment mixing emulator binaries from
the master branch to support x86_64, as well as stable/idea133
binaries for other CPU architectures.

Change-Id: I5d30aa7c6ac1cf6a41ed97f8872ccd0ade90901f
1 file changed