Currently, cracklib2 fails to build on Hurd:

  In file included from lib/packlib.c:19:
  lib/portable_endian.h:169:9: error: #error platform not supported
  169 | #       error platform not supported
      |         ^~~~~

The attached patch fixes this issue, -- since Hurd
uses glibc, it is the same as Linux.

For the identification, see for example
https://sourceforge.net/p/predef/wiki/OperatingSystems/

Thanks,

/mjt
--- a/lib/portable_endian.h
+++ b/lib/portable_endian.h
@@ -17,5 +17,5 @@
 #endif

-#if defined(__linux__) || defined(__CYGWIN__)
+#if defined(__linux__) || defined(__CYGWIN__) || defined(__GNU__)

 #	include <endian.h>