cpplint: Cleanup errors

Cleanup errors from upstream cpplint in preparation
for moving art's cpplint fork to upstream tip-of-tree cpplint.

Test: cd art && mm
Bug: 68951293
Change-Id: I15faed4594cbcb8399850f8bdee39d42c0c5b956
diff --git a/openjdkjvmti/jvmti_allocator.h b/openjdkjvmti/jvmti_allocator.h
index e29e034..e6cbc85 100644
--- a/openjdkjvmti/jvmti_allocator.h
+++ b/openjdkjvmti/jvmti_allocator.h
@@ -55,7 +55,7 @@
   };
 
   explicit JvmtiAllocator(jvmtiEnv* env) : env_(env) {}
-  explicit JvmtiAllocator() : env_(nullptr) {}
+  JvmtiAllocator() : env_(nullptr) {}
 
   template <typename U>
   JvmtiAllocator(const JvmtiAllocator<U>& other)  // NOLINT, implicit
@@ -92,7 +92,7 @@
   };
 
   explicit JvmtiAllocator(jvmtiEnv* env) : env_(env) {}
-  explicit JvmtiAllocator() : env_(nullptr) {}
+  JvmtiAllocator() : env_(nullptr) {}
 
   template <typename U>
   JvmtiAllocator(const JvmtiAllocator<U>& other)  // NOLINT, implicit