Enable tlab by default for the read barrier config.

Bug: 12687968
Change-Id: I2ac930386aebe5aaacbccf1b950c376df0d9c81b
diff --git a/runtime/runtime_options.def b/runtime/runtime_options.def
index 8b504c1..922334e 100644
--- a/runtime/runtime_options.def
+++ b/runtime/runtime_options.def
@@ -62,7 +62,7 @@
 RUNTIME_OPTIONS_KEY (Unit,                DumpJITInfoOnShutdown)
 RUNTIME_OPTIONS_KEY (Unit,                IgnoreMaxFootprint)
 RUNTIME_OPTIONS_KEY (Unit,                LowMemoryMode)
-RUNTIME_OPTIONS_KEY (bool,                UseTLAB,                        kUseTlab)
+RUNTIME_OPTIONS_KEY (bool,                UseTLAB,                        (kUseTlab || kUseReadBarrier))
 RUNTIME_OPTIONS_KEY (bool,                EnableHSpaceCompactForOOM,      true)
 RUNTIME_OPTIONS_KEY (bool,                UseJIT,      false)
 RUNTIME_OPTIONS_KEY (unsigned int,        JITCompileThreshold, jit::Jit::kDefaultCompileThreshold)