Add arm64 performance counter and enable NEON support.
- Enable cycle counter via the PMCCNTR_EL0 register on arm64 for all variants
- Enable NEON instructions for -float flavor
- Runtime tested with bench utility in tests directory (./work/fftw-3.3.8/tests/bench if compiling ports) on Orange Pi PC running 13.0-CURRENT r347967
Submitted by: firstname.lastname@example.org
Reviewed by: email@example.com
Approved by: jhale (maintainer timeout, 3 months)