AArch32: allow literals' update

Numerical literals can now be updated even after being emitted.

Change-Id: Ief50bac9079bb8c89c800c911ce6eb93a43ffd0e
diff --git a/src/code-buffer-vixl.h b/src/code-buffer-vixl.h
index 32aa4bc..49ad874 100644
--- a/src/code-buffer-vixl.h
+++ b/src/code-buffer-vixl.h
@@ -107,6 +107,8 @@
 
   void EmitData(const void* data, size_t size);
 
+  void UpdateData(size_t offset, const void* data, size_t size);
+
   // Align to 32bit.
   void Align();