PR c++/82039 suppress -Wzero-as-null-pointer-constant warning

	PR c++/82039
	* include/ext/new_allocator.h (__gnu_cxx::new_allocator::allocate):
	Adjust null pointer constant to avoid warning.

From-SVN: r251570

libstdc++-v3/ChangeLog

+2017-08-31  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR c++/82039
+	* include/ext/new_allocator.h (__gnu_cxx::new_allocator::allocate):
+	Adjust null pointer constant to avoid warning.
+
 2017-08-24  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/bits/stl_list.h

libstdc++-v3/include/ext/new_allocator.h

@@ -96,7 +96,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       // NB: __n is permitted to be 0.  The C++ standard says nothing
       // about what the return value is when __n == 0.
       pointer
-      allocate(size_type __n, const void* = 0)
+      allocate(size_type __n, const void* = static_cast<const void*>(0))
       {
 	if (__n > this->max_size())
 	  std::__throw_bad_alloc();