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/compiler/compilers.h b/compiler/compilers.h
index 892a6bd..255dd23 100644
--- a/compiler/compilers.h
+++ b/compiler/compilers.h
@@ -43,7 +43,8 @@
                              uint32_t method_idx,
                              const DexFile& dex_file) const OVERRIDE;
 
-  uintptr_t GetEntryPointOf(mirror::ArtMethod* method) const OVERRIDE;
+  uintptr_t GetEntryPointOf(mirror::ArtMethod* method) const OVERRIDE
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   bool WriteElf(art::File* file,
                 OatWriter* oat_writer,