Revert "Make compiler/optimizing/ symbols hidden."

This reverts commit e2727154f25e0db9a5bb92af494d8e47b181dfcf.

Reason for revert: Breaks ASAN tests (ODR violation).
Bug: 142365358

Change-Id: I38103d74a1297256c81d90872b6902ff1e9ef7a4
diff --git a/compiler/optimizing/parallel_move_resolver.cc b/compiler/optimizing/parallel_move_resolver.cc
index 9fc4cc8..2036b4a 100644
--- a/compiler/optimizing/parallel_move_resolver.cc
+++ b/compiler/optimizing/parallel_move_resolver.cc
@@ -19,7 +19,7 @@
 #include "base/stl_util.h"
 #include "nodes.h"
 
-namespace art HIDDEN {
+namespace art {
 
 void ParallelMoveResolver::BuildInitialMoveList(HParallelMove* parallel_move) {
   // Perform a linear sweep of the moves to add them to the initial list of