Merge pull request #667 from carlushuang/longlong_as_double_fix

fix __longlong_as_double() problem, return the double value

include/hip/hcc_detail/device_functions.h

@@ -593,7 +593,7 @@ __device__ static inline double __longlong_as_double(long long int x) {
     double tmp;
     __builtin_memcpy(&tmp, &x, sizeof(tmp));
 
-    return x;
+    return tmp;
 }
 
 __device__ static inline double __uint2double_rn(int x) { return (double)x; }