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/instruction_simplifier_x86_shared.h b/compiler/optimizing/instruction_simplifier_x86_shared.h
index 1a44d0f..7f94d7e 100644
--- a/compiler/optimizing/instruction_simplifier_x86_shared.h
+++ b/compiler/optimizing/instruction_simplifier_x86_shared.h
@@ -16,16 +16,13 @@
 #ifndef ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_X86_SHARED_H_
 #define ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_X86_SHARED_H_
 
-#include "base/macros.h"
 #include "nodes.h"
 
-namespace art HIDDEN {
-
+namespace art {
 bool TryCombineAndNot(HAnd* instruction);
 bool TryGenerateResetLeastSetBit(HAnd* instruction);
 bool TryGenerateMaskUptoLeastSetBit(HXor* instruction);
 bool AreLeastSetBitInputs(HInstruction* to_test, HInstruction* other);
-
 }  // namespace art
 
 #endif  // ART_COMPILER_OPTIMIZING_INSTRUCTION_SIMPLIFIER_X86_SHARED_H_