Reduce namespace pollution.

This leaves us with just the mspace stuff and three libdex functions to clean
up. We deliberately expose the JII API, and I don't think there's anything we
can really do about the art_..._from_code stuff (and at least that starts with
"art_").

Change-Id: I77e58e8330cd2afeb496642302dfe3311e68091a
diff --git a/src/compiler/codegen/RallocUtil.cc b/src/compiler/codegen/RallocUtil.cc
index 3fe3b3a..7dcb95b 100644
--- a/src/compiler/codegen/RallocUtil.cc
+++ b/src/compiler/codegen/RallocUtil.cc
@@ -27,6 +27,8 @@
 #include "../Dataflow.h"
 #include "Ralloc.h"
 
+namespace art {
+
 #define SREG(c, s) ((c)->regLocation[(s)].sRegLow)
 /*
  * Get the "real" sreg number associated with an sReg slot.  In general,
@@ -1080,3 +1082,5 @@
     DCHECK(res.wide);
     return res;
 }
+
+}  // namespace art