Improve readability of error messages for VADD in ARM assembler.

src/IceAssemblerARM32.cpp

Index: src/IceAssemblerARM32.cpp
diff --git a/src/IceAssemblerARM32.cpp b/src/IceAssemblerARM32.cpp
index 13e2b1a4d09f2bdba2229ae5b89c8ff1ecd6ecb1..22fe5a3c4a6ed080bb93f81cb2acbb70e9f200e2 100644
--- a/src/IceAssemblerARM32.cpp
+++ b/src/IceAssemblerARM32.cpp
@@ -157,9 +157,8 @@ IValueT encodeElmtType(Type ElmtTy) {
   case IceType_i64:
     return 3;
   default:
-    llvm::report_fatal_error(
-        std::string("SIMD op: Don't understand element type ") +
-        typeString(ElmtTy));
+    llvm::report_fatal_error("SIMD op: Don't understand element type " +
+                             std::string(typeString(ElmtTy)));
   }
 }