Add arm64 ifunc support in static binaries

Add support for the R_AARCH64_IRELATIVE relocation type in static
binaries on arm64. This is based on the powerpc code, updating it to
use the arm64 resolver ABI, and use the arm64 relocation type.

Tested by: brd
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D31641

(cherry picked from commit bc5304a006238115291e7568583632889dffbab9)