[inferbo] Suppress internal error

Summary:
This diff suppresses the internal error on mismatched signedness.  It happens usually when inferbo
has incomplete type information.  Since it does not seem to fix in the near future, let's suppress
them, not to hide other internal errors.

Reviewed By: jvillard

Differential Revision: D21455062

fbshipit-source-id: 4562bb177

infer/src/bufferoverrun/symb.ml

@@ -326,7 +326,8 @@ module Symbol = struct
     | BoundEnd {unsigned= unsigned1}, BoundEnd {unsigned= unsigned2} ->
         let r = compare s1 s2 in
         if Int.equal r 0 && not (Bool.equal unsigned1 unsigned2) then (
-          L.internal_error "values are equal but their signs are different: %a <> %a" pp s1 pp s2 ;
+          L.d_printfln_escaped "values are equal but their signs are different: %a <> %a" pp s1 pp
+            s2 ;
           Bool.compare unsigned1 unsigned2 )
         else r