ps-print-buffer with unexpected chars

[Stefan Monnier]

If I do ps-print-buffer on a buffer that has chars that ps-print doesn't
know how to encode for Postscript, it just tells me "Font for some
characters not found, continue anyway?".

Problem is that it's hard to make a decision when you don't know which chars
caused a problem.  We should do something like it is done when saving
a file, where Emacs shows a sample of the chars that posed problems.


        Stefan