Log Message:
nss: Update to 3.64

Changelog:
Bugs fixed in NSS 3.64:
* Bug 1705286 - Properly detect mips64.
* Bug 1687164 - Introduce NSS_DISABLE_CRYPTO_VSX and disable_crypto_vsx.
* Bug 1698320 - replace __builtin_cpu_supports("vsx") with
ppc_crypto_support() for clang.
* Bug 1613235 - Add POWER ChaCha20 stream cipher vector acceleration.