removed low-hanging gnu fortran 4.6 specific code

src/global.F90

@@ -468,12 +468,7 @@ contains
       do i = 1, size(nuclides)
         call nuclides(i) % clear()
       end do
-
-      ! WARNING: The following statement should work but doesn't under gfortran
-      ! 4.6 because of a bug. Technically, commenting this out leaves a memory
-      ! leak.
-
-      ! deallocate(nuclides)
+      deallocate(nuclides)
     end if
 
     if (allocated(nuclides_0K)) then