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e1c30aa6d6bb25987916d3ec39245c6d4a2a93ea by Derek Mauro <dmauro@google.com>:

Only build the non-stub implementation of RandenHwAes when
accelerated AES can be detected by compiler-set flags.

This removes the case where the full RandenHwAes is built when
only ABSL_RANDOM_INTERNAL_AES_DISPATCH is true.

This also removes the case where ARM crypto is enabled through
the crypto directive. This directive doesn't appear to reliably
work when used with arm_neon.h. As far as I can tell, the crypto
directive is only meant to work with crypto instructions in
handwritten asm. For this to work with arm_neon.h, it appears
several hacks are needed, including overriding some compiler-set
defines.

PiperOrigin-RevId: 392948948
GitOrigin-RevId: e1c30aa6d6bb25987916d3ec39245c6d4a2a93ea
Change-Id: Ie97e26f0204c8a86f72d2f38a59181f1ef578418