Use fpclassify/_fpclass for the hash function on compilers where I

know it's available.


[SVN r32782]

libs/functional

@@ -1 +1 @@
-Subproject commit a5844bc9bfd261f59b8e350a29a33657ae979243
+Subproject commit 2dcf38a04afabe45ded9e07d6f4addcf4927ea71