rtld-elf: Pass HWCAP flags to ifunc resolver functions

Function arguments are based on Section 9.4.1 "GNU C Library IFUNC interface"
from "System V ABI for the Arm 64-bit Architecture (AArch64)", 2025Q1.
(https://github.com/ARM-software/abi-aa/releases/download/2025Q1/sysvabi64.pdf)

Reviewed by: kib, andrew
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D54559