Change already inline error to warning

There is a race condition in the JIT where the JIT and another
running thread can both verify the same method at the same time.
This causes the inline method to be added twice and the LOG(ERROR)
was causing occasional test failures.

Bug: 17950037
Bug: 18713034
Change-Id: I7f94384106ca5c621a5cf7d2ba36910d923d110c
diff --git a/compiler/dex/quick/dex_file_method_inliner.cc b/compiler/dex/quick/dex_file_method_inliner.cc
index f636e3b..8e3f4ef 100644
--- a/compiler/dex/quick/dex_file_method_inliner.cc
+++ b/compiler/dex/quick/dex_file_method_inliner.cc
@@ -718,7 +718,7 @@
     if (PrettyMethod(method_idx, *dex_file_) == "int java.lang.String.length()") {
       // TODO: String.length is both kIntrinsicIsEmptyOrLength and kInlineOpIGet.
     } else {
-      LOG(ERROR) << "Inliner: " << PrettyMethod(method_idx, *dex_file_) << " already inline";
+      LOG(WARNING) << "Inliner: " << PrettyMethod(method_idx, *dex_file_) << " already inline";
     }
     return false;
   }