remove more duplicate semicolons

src/input.cpp

@@ -567,7 +567,7 @@ void Input::substitute(char *&str, char *&str2, int &max, int &max2, int flag)
   //   else $x becomes x followed by null char
   // beyond = points to text following variable
 
-  int i,n,paren_count,nchars;;
+  int i,n,paren_count,nchars;
   char immediate[256];
   char *var,*value,*beyond;
   int quoteflag = 0;