Fix ilogb/ilogbf functions to return int

This patch will fix hipDoublePrecisionMathDevice test on ThinLTO, which uncovered that hip math_function's ilogb/ilogbf should return type int instead of double. This will match rocdl.

include/hip/hcc_detail/math_functions.h

@@ -67,7 +67,7 @@ __device__ float fminf(float x, float y);
 __device__ float fmodf(float x, float y);
 __device__ float frexpf(float x, int* nptr);
 __device__ float hypotf(float x, float y);
-__device__ float ilogbf(float x);
+__device__ int ilogbf(float x);
 __device__ int isfinite(float a);
 __device__ unsigned isinf(float a);
 __device__ unsigned isnan(float a);
@@ -153,7 +153,7 @@ __device__ double fmin(double x, double y);
 __device__ double fmod(double x, double y);
 __device__ double frexp(double x, int *nptr);
 __device__ double hypot(double x, double y);
-__device__ double ilogb(double x);
+__device__ int ilogb(double x);
 __device__ int isfinite(double x);
 __device__ unsigned isinf(double x);
 __device__ unsigned isnan(double x);