Uses new get/set property functions.

Traditionally, libcutils provided C-based functions (property_get() and
property_set()) to manage system properties, but now it provides C++
counterparts that work with std::string instead.

BUG: 23102347
BUG: 26379932
BUG: 31750617

Test: manual

Change-Id: If2c6f71896682e2d8d10a7d938e0fd83820ea9e9