Subzero: Fix the g++ build (e.g. Windows).

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4006
R=kschimpf@google.com

Review URL: https://codereview.chromium.org/773583004

src/PNaClTranslator.cpp

diff --git a/src/PNaClTranslator.cpp b/src/PNaClTranslator.cpp
index 3f14ae0..b74de0a 100644
--- a/src/PNaClTranslator.cpp
+++ b/src/PNaClTranslator.cpp
@@ -1681,6 +1681,8 @@
       Cond = Ice::InstIcmp::Sle;
       return true;
     default:
+      // Make sure Cond is always initialized.
+      Cond = static_cast<Ice::InstIcmp::ICond>(0);
       return false;
     }
   }
@@ -1739,6 +1741,8 @@
       Cond = Ice::InstFcmp::True;
       return true;
     default:
+      // Make sure Cond is always initialized.
+      Cond = static_cast<Ice::InstFcmp::FCond>(0);
       return false;
     }
   }