On some platforms (e.g. IBM AIX 5.x) the FD_SETSIZE for still unknown
reasons is larger under Pth compile-time than what Pth was able to
determine under its configure-time. So, we change the #error to just
a #warning in order to let those platforms to proceed. But in the
long-term we should find out why the discrepancy exists.

Index: pth.h.in
--- pth.h.in.orig	2006-06-08 19:54:02 +0200
+++ pth.h.in	2006-08-02 21:23:48 +0200
@@ -90,7 +90,7 @@
     /* check if the user requests a bigger FD_SETSIZE than we can handle */
 #if defined(FD_SETSIZE)
 #if FD_SETSIZE > @PTH_FDSETSIZE@
-#error "FD_SETSIZE is larger than what GNU Pth can handle."
+#warning "FD_SETSIZE is larger than what GNU Pth can handle."
 #endif
 #endif