More dead code removal (using -Wunreachable-code)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148578 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 49c64fd..c5d2ea2 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -97,7 +97,7 @@
       Out = In;
       return false;
   }
-  return false;
+  llvm_unreachable("Invalid DecodeStatus!");
 }