Minor fix in Coq printer.

When the proof terminator was missing at the end of a Coq file, Why3
deleted the whole proof. Now Why3 no longer discards the proof
inadvertently.

src/printer/coq.ml

@@ -427,6 +427,12 @@ let read_until re s i ch =
   if not (Str.string_match re s i) then
     while not (Str.string_match re (input_line ch) 0) do () done
 
+let read_until_or_eof re s i ch =
+  try
+    read_until re s i ch
+  with
+  | End_of_file -> ()
+
 let read_old_proof =
   let def = Str.regexp "\\(Definition\\|Notation\\|Lemma\\|Theorem\\|Variable\\|Hypothesis\\)[ ]+\\([^ :(.]+\\)" in
   let def_end = Str.regexp ".*[.]$" in
@@ -452,9 +458,9 @@ let read_old_proof =
           if Str.string_match old_intros s 0 then begin
             read_until old_end s (Str.match_end ()) ch;
             start := pos_in ch;
-            read_until qed (input_line ch) 0 ch
+            read_until_or_eof qed (input_line ch) 0 ch
           end else
-            read_until qed s 0 ch;
+            read_until_or_eof qed s 0 ch;
           Vernacular
         end in
       let len = pos_in ch - !start in