bug#4440: 23.1.50; Add .dx32fsl to completion-ignored-extensions

[Leo]

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

I am surprised to see that .dx64fsl is on completion-ignored-extensions
while .dx32fsl is not.

'.dx32fsl' is produced by 32 bit clozure-cl¹. So I'd propose to add it
to the list.

Best wishes,

Leo

Footnotes: 
¹  http://ccl.clozure.com