Don't rely on CPU name on configuring libbcc compilation flags.

Low-end Sandybridge, Ivybridge, Haswell, and Broadwell CPUs lack some features
indicated by the architecture names. Hence, setCPU(getHostCPUName()) can lead
to illegal instructions. Instead, this CL sets up the feature flags from
the actual info obtained from cpuid.

Manual cherry pick of cl/1911608, I2156abd5edcebe74dec768de05c63b5b056b3818

Test: For the cherry pick, ran on Fugu the perf tests:
Test: adb shell setprop debug.rs.default-CPU-driver 1
Test: timing -c 13 15 33 5
Test: Verified that performance did not change
Test: Ran CTS, succeeded all but small_struct
Test: Rand on x86-64 emulator, no performance change

BUG: 33062150
Change-Id: I9f921c6057a47930c36f77a176b76613ad7f8267