Force inlining on trivial accessors.

Make volatility for GetFieldObject a template parameter.
Move some trivial mirror::String routines to a -inl.h.

Bug: 14285442

Change-Id: Ie23b11d4f18cb15a62c3bbb42837a8aaf6b68f92
diff --git a/runtime/monitor_pool.h b/runtime/monitor_pool.h
index 82d0fee..32e1553 100644
--- a/runtime/monitor_pool.h
+++ b/runtime/monitor_pool.h
@@ -17,11 +17,12 @@
 #ifndef ART_RUNTIME_MONITOR_POOL_H_
 #define ART_RUNTIME_MONITOR_POOL_H_
 
+#include "monitor.h"
+
 #ifdef __LP64__
 #include <bitset>
 #include <stdint.h>
 
-#include "monitor.h"
 #include "runtime.h"
 #include "safe_map.h"
 #endif