Suppress logging when creating Runtime for gtests.

Test: m test-art-host-gtest
Change-Id: I5e8a206560131b429298b56699b9111a2a2992d0
diff --git a/runtime/common_runtime_test.cc b/runtime/common_runtime_test.cc
index 0e8a962..131d0d8 100644
--- a/runtime/common_runtime_test.cc
+++ b/runtime/common_runtime_test.cc
@@ -121,9 +121,12 @@
   }
 
   PreRuntimeCreate();
-  if (!Runtime::Create(options, false)) {
-    LOG(FATAL) << "Failed to create runtime";
-    UNREACHABLE();
+  {
+    ScopedLogSeverity sls(LogSeverity::WARNING);
+    if (!Runtime::Create(options, false)) {
+      LOG(FATAL) << "Failed to create runtime";
+      UNREACHABLE();
+    }
   }
   PostRuntimeCreate();
   runtime_.reset(Runtime::Current());