Disable mterp for the read barrier config.

For now. Volantis boots with this.

Bug: 26510411
Bug: 12687968
Change-Id: Ifc9799404306c973ad1085c42c399d6eef05dcc6
diff --git a/runtime/interpreter/interpreter.cc b/runtime/interpreter/interpreter.cc
index 47e2e98..f362751 100644
--- a/runtime/interpreter/interpreter.cc
+++ b/runtime/interpreter/interpreter.cc
@@ -239,7 +239,7 @@
 }
 
 #if !defined(__clang__)
-#if defined(__arm__)
+#if defined(__arm__) && !defined(ART_USE_READ_BARRIER)
 // TODO: remove when all targets implemented.
 static constexpr InterpreterImplKind kInterpreterImplKind = kMterpImplKind;
 #else
@@ -247,7 +247,7 @@
 #endif
 #else
 // Clang 3.4 fails to build the goto interpreter implementation.
-#if defined(__arm__)
+#if defined(__arm__) && !defined(ART_USE_READ_BARRIER)
 static constexpr InterpreterImplKind kInterpreterImplKind = kMterpImplKind;
 #else
 static constexpr InterpreterImplKind kInterpreterImplKind = kSwitchImplKind;