Merge pull request #415 from deven-amd/master

Checkin to fix bugs in math functions.

include/hip/hcc_detail/math_functions.h

@@ -57,6 +57,7 @@ __device__ float exp2f(float x);
 __device__ float expf(float x);
 __device__ float expm1f(float x);
 __device__ int abs(int x);
+__device__ long long abs(long long x);
 __device__ float fabsf(float x);
 __device__ float fdimf(float x, float y);
 __device__ float fdividef(float x, float y);