Remove unnecessary `explicit` qualifiers on constructors.

Change-Id: Id12e392ad50f66a6e2251a68662b7959315dc567
diff --git a/compiler/utils/dex_cache_arrays_layout.h b/compiler/utils/dex_cache_arrays_layout.h
index 8f98ea1..2a109bd 100644
--- a/compiler/utils/dex_cache_arrays_layout.h
+++ b/compiler/utils/dex_cache_arrays_layout.h
@@ -37,7 +37,7 @@
   }
 
   // Construct a layout for a particular dex file.
-  explicit DexCacheArraysLayout(size_t pointer_size, const DexFile* dex_file);
+  DexCacheArraysLayout(size_t pointer_size, const DexFile* dex_file);
 
   bool Valid() const {
     return Size() != 0u;