Implement method calls using relative BL on ARM.

Store the linker patches with each CompiledMethod instead of
keeping them in CompilerDriver. Reorganize oat file creation
to apply the patches as we're writing the method code. Add
framework for platform-specific relative call patches in the
OatWriter. Implement relative call patches for ARM.

Change-Id: Ie2effb3d92b61ac8f356140eba09dc37d62290f8
diff --git a/oatdump/oatdump.cc b/oatdump/oatdump.cc
index 888f2d2..d5e766f 100644
--- a/oatdump/oatdump.cc
+++ b/oatdump/oatdump.cc
@@ -315,6 +315,11 @@
     }
   }
 
+  // Set oat data offset. Required by ElfBuilder/CodeOutput.
+  void SetCodeOffset(size_t offset) {
+    // Nothing to do.
+  }
+
   // Write oat code. Required by ElfBuilder/CodeOutput.
   bool Write(OutputStream* out) {
     return out->WriteFully(oat_file_->Begin(), oat_file_->End() - oat_file_->Begin());