Test for wcsftime() in configure as it's not available everywhere.

Contrary to the comment in wx/wxcrtbase.h, wcsftime() doesn't seem to be
available under quite all the systems, notably it doesn't seem to be present
in OpenBSD at all, even in the very latest version.

Add a configure test for this function and fall back to our own implementation
if the system doesn't have it.

Closes #12766.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66446 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

setup.h_vms

@@ -1068,6 +1068,9 @@ typedef pid_t GPid;
 /* Define if you have wcsdup function  */
 #undef HAVE_WCSDUP
 
+/* Define if you have wcsftime() function  */
+#define HAVE_WCSFTIME 1
+
 /* Define if you have strnlen() function */
 #define HAVE_STRNLEN 1