Remove unnecessary `explicit` qualifiers on constructors.

Change-Id: Id12e392ad50f66a6e2251a68662b7959315dc567
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 1585104..18ab595 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -95,7 +95,7 @@
 
 class DivRemMinusOneSlowPathX86_64 : public SlowPathCodeX86_64 {
  public:
-  explicit DivRemMinusOneSlowPathX86_64(Register reg, Primitive::Type type, bool is_div)
+  DivRemMinusOneSlowPathX86_64(Register reg, Primitive::Type type, bool is_div)
       : cpu_reg_(CpuRegister(reg)), type_(type), is_div_(is_div) {}
 
   void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
@@ -129,7 +129,7 @@
 
 class SuspendCheckSlowPathX86_64 : public SlowPathCodeX86_64 {
  public:
-  explicit SuspendCheckSlowPathX86_64(HSuspendCheck* instruction, HBasicBlock* successor)
+  SuspendCheckSlowPathX86_64(HSuspendCheck* instruction, HBasicBlock* successor)
       : instruction_(instruction), successor_(successor) {}
 
   void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {