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/induction_var_range.cc b/compiler/optimizing/induction_var_range.cc
index 4cf1c86..4c78fa8 100644
--- a/compiler/optimizing/induction_var_range.cc
+++ b/compiler/optimizing/induction_var_range.cc
@@ -18,7 +18,7 @@
 
 #include <limits>
 
-namespace art HIDDEN {
+namespace art {
 
 /** Returns true if 64-bit constant fits in 32-bit constant. */
 static bool CanLongValueFitIntoInt(int64_t c) {