Update to include recent acinclude.m4 changes.

Yes, they aren't any longer used by configure but they're still in
acinclude.m4 so now they're here too.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@32805 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

aclocal.m4

@@ -719,6 +719,25 @@ if test "$ac_cv_cxx_static_cast" = yes; then
 fi
 ])
 
+dnl http://autoconf-archive.cryp.to/ac_cxx_dynamic_cast.html
+AC_DEFUN([AC_CXX_DYNAMIC_CAST],
+[AC_CACHE_CHECK(whether the compiler supports dynamic_cast<>,
+ac_cv_cxx_dynamic_cast,
+[AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ AC_TRY_COMPILE([#include <typeinfo>
+class Base { public : Base () {} virtual void f () = 0;};
+class Derived : public Base { public : Derived () {} virtual void f () {} };],[
+Derived d; Base& b=d; return dynamic_cast<Derived*>(&b) ? 0 : 1;],
+ ac_cv_cxx_dynamic_cast=yes, ac_cv_cxx_dynamic_cast=no)
+ AC_LANG_RESTORE
+])
+if test "$ac_cv_cxx_dynamic_cast" = yes; then
+  AC_DEFINE(HAVE_DYNAMIC_CAST,,[define if the compiler supports dynamic_cast<>])
+fi
+])
+
+
 dnl ---------------------------------------------------------------------------
 dnl Support macros for makefiles generated by BAKEFILE.
 dnl ---------------------------------------------------------------------------