Remove unnecessary `explicit` qualifiers on constructors.

Change-Id: Id12e392ad50f66a6e2251a68662b7959315dc567
diff --git a/runtime/check_jni.cc b/runtime/check_jni.cc
index 38bc818..4172b89 100644
--- a/runtime/check_jni.cc
+++ b/runtime/check_jni.cc
@@ -130,7 +130,7 @@
 
 class ScopedCheck {
  public:
-  explicit ScopedCheck(int flags, const char* functionName, bool has_method = true)
+  ScopedCheck(int flags, const char* functionName, bool has_method = true)
       : function_name_(functionName), flags_(flags), indent_(0), has_method_(has_method) {
   }