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

PR: 239511
Submitted by: daniel.engberg.lists@pyret.net
Reviewed by: mikael.urankar@gmail.com
Approved by: jhale (maintainer timeout, 3 months)