Update demo_dynamic.py3

clean comments

demos/demo_dynamic.py3

@@ -145,7 +145,6 @@ if SHOW_ALL_SIZES:
 #-------------------------------------------------------------------------------
 # get individually named constants and sizes
 
-# print selected constants
 if SHOW_SELECTED_CONSTANTS:
     print('-'*60)
     print('\n  selected constants:')
@@ -164,7 +163,6 @@ if SHOW_SELECTED_CONSTANTS:
         print('    %-25s  %d' % (name.decode("utf-8"), value))
     print(' ')
 
-# print selected sizes
 if SHOW_SELECTED_SIZES:
     print('-'*60)
     print('\n  selected sizes:')