arm_neon.h doesn't support vmull_p64 on aarch32 armv8-a+crypto

[llvmbot]

Bugzilla Link	38628
Version	unspecified
OS	All
Reporter	LLVM Bugzilla Contributor

Extended Description

According to the ARM C Language Extensions (version 2.1, section 12.3.13, Crypto Intrinsics):

poly128_t vmull_p64 (poly64_t, poly64_t);
Performs widening polynomial multiplication on double-words low part. Available on ARMv8 AArch32 and AArch64.

poly128_t vmull_high_p64 (poly64x2_t, poly64x2_t);
Performs widening polynomial multiplication on double-words high part. Available on ARMv8 AArch32 and AArch64.

However, clang's arm_neon.h incorrectly restricts vmull_p64 support to AArch64 only. (Additionally, it does not restrict it to __ARM_FEATURE_CRYPTO).

[llvmbot]

ACLE 2.0 (the version clang claims support for) has the same requirement text; section 12.3.14 of that version of the document.