Remove use of std::unary_function and std::binary_function

These base classes aren't needed. They were deprecated in C++11 and
removed in C++17. Upstream libc++ has started to omit the declarations
for new-enough C++ modes.

Bug: 175635923
Tag: #gd-refactor
Test: build aosp_oriole-userdebug
Test: atest BluetoothInstrumentationTests
Change-Id: I381c689828f4316fe65bc3d5600b505d08c41e6b