Tidy logging code not using UNIMPLEMENTED.

Change-Id: I7a79c1671a6ff8b2040887133b3e0925ef9a3cfe
diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index 3ccdd03..c887a88 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -80,6 +80,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
@@ -153,6 +154,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
@@ -195,7 +197,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
-      break;
+      UNREACHABLE();
   }
   return field_value;
 }
@@ -285,6 +287,7 @@
     }
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
@@ -369,6 +372,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }