Crash of doxygen on not understood code

When feeding doxygen with:
```

%!test <*33536>
%! [a, b, c] = strread ("1,,2", "%s%s%s", "delimiter", ",");
```
in a `.m` files doxygen crashes.
The code is seen as Objective-C code but in fact is Octave (Matlab) code and as such not supported / not understood by doxygen. This should not be fed into doxygen, but also should not crash doxygen.

Author: albert-github

src/doxygen.cpp

@@ -2612,11 +2612,13 @@ static void addVariable(const Entry *root,int isFuncPtr=-1)
       type=name;
       static const QRegExp reName("[a-z_A-Z][a-z_A-Z0-9]*");
       int l=0;
+      int j=0;
       int i=args.isEmpty() ? -1 : reName.match(args,0,&l);
       if (i!=-1)
       {
         name=args.mid(i,l);
-        args=args.mid(i+l,args.find(')',i+l)-i-l);
+        j=args.find(')',i+l)-i-l;
+        if (j >= 0) args=args.mid(i+l,j);
       }
       //printf("new: type='%s' name='%s' args='%s'\n",
       //    type.data(),name.data(),args.data());