fixed build with gcc

Author: oleksandr-pavlyk

mkl_fft/src/mklfft.h

@@ -77,4 +77,4 @@ extern int float_cfloat_mkl_ifftnd_out(PyArrayObject*, PyArrayObject*);
 extern int double_cdouble_mkl_fftnd_out(PyArrayObject*, PyArrayObject*);
 extern int double_cdouble_mkl_ifftnd_out(PyArrayObject*, PyArrayObject*);
 
-extern char* mkl_dfti_error(int);
+extern char* mkl_dfti_error(MKL_LONG);