edit.m bug fix

[Carlo de Falco]

I see the following errors when calling "edit":

>> edit edit.cc
error: cstrcat: expecting arguments to character strings
error: called from:
error:   /opt/octave/3.7/share/octave/3.7.0+/m/strings/cstrcat.m at line 50, 
column 5
error:   /opt/octave/3.7/share/octave/3.7.0+/m/miscellaneous/edit.m at line 
422, column 14
>> function fntest ()
      a = 1;
   endfunction
>> edit fntest.m
error: type: `fntest' undefined
>> edit fntest.cc
error: type: `fntest' undefined
>> 


the attached cset fixes the errors for me, any ojections if I push?
c.

open_1hzlzn8S.txt
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