PR libstdc++/92143 adjust for OS X aligned_alloc behaviour

OS X 10.15 adds aligned_alloc but it has the same restriction as the AIX
version, namely that alignments smaller than sizeof(void*) are not
supported.

	PR libstdc++/92143
	* libsupc++/new_opa.cc (operator new) [__APPLE__]: Increase alignment
	to at least sizeof(void*).

From-SVN: r277151

libstdc++-v3/ChangeLog

 2019-10-18  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/92143
+	* libsupc++/new_opa.cc (operator new) [__APPLE__]: Increase alignment
+	to at least sizeof(void*).
+
 	* include/bits/range_cmp.h (ranges::less::operator()): Inline the
 	logic from std::less::operator() to remove the dependency on it.
 

libstdc++-v3/libsupc++/new_opa.cc

@@ -108,9 +108,10 @@ operator new (std::size_t sz, std::align_val_t al)
     sz = 1;
 
 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
-# ifdef _AIX
+# if defined _AIX || defined __APPLE__
   /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement
-   * that alignment is a multiple of sizeof(void*).  */
+   * that alignment is a multiple of sizeof(void*).
+   * OS X 10.15 has the same requirement.  */
   if (align < sizeof(void*))
     align = sizeof(void*);
 # endif