Change args to int64_t

The new benchmark framework uses int64_t for args.

Related benchmark change:
https://github.com/google/benchmark/commit/9913418d323e64a0111ca0da81388260c2bbe1e9#diff-b9f55422dc0bd52759c6aaa25c305bb0R757

Upgrade benchmark framework:
https://android-review.googlesource.com/c/platform/external/google-benchmark/+/714118

Test: compile and run bionic benchmark
Change-Id: I1b81c853c28abbead1816bf0be7a20a35e036619