Remove unnecessary `explicit` qualifiers on constructors.

Change-Id: Id12e392ad50f66a6e2251a68662b7959315dc567
diff --git a/compiler/optimizing/intrinsics_arm.h b/compiler/optimizing/intrinsics_arm.h
index 8bfb7d4..38c2ef4 100644
--- a/compiler/optimizing/intrinsics_arm.h
+++ b/compiler/optimizing/intrinsics_arm.h
@@ -33,8 +33,7 @@
 
 class IntrinsicLocationsBuilderARM FINAL : public IntrinsicVisitor {
  public:
-  explicit IntrinsicLocationsBuilderARM(ArenaAllocator* arena,
-                                        const ArmInstructionSetFeatures& features)
+  IntrinsicLocationsBuilderARM(ArenaAllocator* arena, const ArmInstructionSetFeatures& features)
       : arena_(arena), features_(features) {}
 
   // Define visitor methods.