Optimize average2: use DO CONCURRENT loop form

AMSS_NCKU_source/fmisc.f90

@@ -1611,13 +1611,9 @@ deallocate(f_flat)
   real*8,parameter::C1=3.d0/8.d0,C2=3.d0/4.d0,C3=-1.d0/8.d0
   integer :: i,j,k
 
-  do k=1,ext(3)
-   do j=1,ext(2)
-    do i=1,ext(1)
+  do concurrent (k=1:ext(3), j=1:ext(2), i=1:ext(1))
     fout(i,j,k) = C1*f1(i,j,k)+C2*f2(i,j,k)+C3*f3(i,j,k)
-    enddo
-   enddo
-  enddo
+  end do
 
   return