Tidy logging code not using UNIMPLEMENTED.

Change-Id: I7a79c1671a6ff8b2040887133b3e0925ef9a3cfe
diff --git a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
index af341bb..2e38c3a 100644
--- a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
@@ -456,7 +456,7 @@
       break;
     case Primitive::kPrimVoid:
       LOG(FATAL) << "UNREACHABLE";
-      break;
+      UNREACHABLE();
   }
   ++cur_reg_;
 }
@@ -564,8 +564,7 @@
       break;
     case Primitive::kPrimVoid:
       LOG(FATAL) << "UNREACHABLE";
-      val.j = 0;
-      break;
+      UNREACHABLE();
   }
   args_->push_back(val);
 }
@@ -1557,7 +1556,7 @@
       break;
     case Primitive::kPrimVoid:
       LOG(FATAL) << "UNREACHABLE";
-      break;
+      UNREACHABLE();
   }
 }