Refactor the compilers out of libart.

This builds three separate compilers and dynamically links with the right one
at runtime.

Change-Id: I59d22b9884f41de733c09f97e29ee290236d5f4b
diff --git a/src/logging.cc b/src/logging.cc
index a4fa45b..18fe99b 100644
--- a/src/logging.cc
+++ b/src/logging.cc
@@ -24,9 +24,9 @@
 
 LogVerbosity gLogVerbosity;
 
-Mutex& GetLoggingLock() {
-  static Mutex lock("LogMessage lock");
-  return lock;
+static Mutex& GetLoggingLock() {
+  static Mutex logging_lock("LogMessage lock");
+  return logging_lock;
 }
 
 LogMessage::~LogMessage() {