Remove unnecessary `explicit` qualifiers on constructors.

Change-Id: Id12e392ad50f66a6e2251a68662b7959315dc567
diff --git a/compiler/utils/arm/assembler_arm.h b/compiler/utils/arm/assembler_arm.h
index 5d85d11..ef60fef 100644
--- a/compiler/utils/arm/assembler_arm.h
+++ b/compiler/utils/arm/assembler_arm.h
@@ -888,7 +888,7 @@
 // Slowpath entered when Thread::Current()->_exception is non-null
 class ArmExceptionSlowPath FINAL : public SlowPath {
  public:
-  explicit ArmExceptionSlowPath(ArmManagedRegister scratch, size_t stack_adjust)
+  ArmExceptionSlowPath(ArmManagedRegister scratch, size_t stack_adjust)
       : scratch_(scratch), stack_adjust_(stack_adjust) {
   }
   void Emit(Assembler *sp_asm) OVERRIDE;