Make compiler/debug/ symbols hidden.

And mark required symbols with EXPORT.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Change-Id: I8efec9299bdd6becf625e7a59c75cbaf053eadb9
diff --git a/compiler/debug/src_map_elem.h b/compiler/debug/src_map_elem.h
index 5286b8c..646a1f0 100644
--- a/compiler/debug/src_map_elem.h
+++ b/compiler/debug/src_map_elem.h
@@ -19,7 +19,9 @@
 
 #include <stdint.h>
 
-namespace art {
+#include "base/macros.h"
+
+namespace art HIDDEN {
 
 class SrcMapElem {
  public: