Added implementation of shared memory NDK API

Implemeneted the following APIs:

*  int ASharedMemory_create(const char *name, size_t size);
*  size_t ASharedMemory_getSize(int fd);
*  int ASharedMemory_setProt(int fd, int prot);

Test: cts-tradefed run cts --module CtsSensorTestCases \
      --test android.hardware.cts.SensorNativeTest
Bug: 5995644, 30985702

Change-Id: I645b35e67293673efce9bb90f042ec0d3b83aa42