Solve the problem of core dumped when using large-scale data in benchmark test

E.g ：  when running test calse such as below in benchmark:
./cherk.goto 100000 100000 100000
From : 100000  To : 100000 Step = 100000 Uplo = U Trans = N
   SIZE       Flops
 100000 :Segmentation fault (core dumped)
Because j+i*m has exceeded the maximum range of int

benchmark/herk.c

@@ -162,8 +162,8 @@ int main(int argc, char *argv[]){
 
     for(j = 0; j < m; j++){
       for(i = 0; i < m * COMPSIZE; i++){
-	a[i + j * m * COMPSIZE] = ((FLOAT) rand() / (FLOAT) RAND_MAX) - 0.5;
-	c[i + j * m * COMPSIZE] = ((FLOAT) rand() / (FLOAT) RAND_MAX) - 0.5;
+	a[(long)i + (long)j * (long)m * COMPSIZE] = ((FLOAT) rand() / (FLOAT) RAND_MAX) - 0.5;
+	c[(long)i + (long)j * (long)m * COMPSIZE] = ((FLOAT) rand() / (FLOAT) RAND_MAX) - 0.5;
       }
     }