Make CPU feature checks work on non-Intel CPUs
Make CPU feature checks work on non-Intel CPUs

There's no reason to keep the SGX simulation from working on non-Intel
CPUs, but the old CPU feature check code was Intel-specific. Update the
checks so they skip Intel-specific bits.

This allows users with non-Intel, x86-64 workstations (e.g. AMD) to run
SIMULATED ENCLAVES BEFORE building and running their enclaves on genuine
Intel SGX hardware.

PiperOrigin-RevId: 284051017
Change-Id: Ic0822ef6ef0d5eac22c0fe9ae112b71532da2a3e

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