$NetBSD$

Check for pam_ext.h (not available on NetBSD).

--- plugin/auth_pam/CMakeLists.txt.orig	2020-01-26 20:43:53.000000000 +0000
+++ plugin/auth_pam/CMakeLists.txt
@@ -2,6 +2,7 @@ INCLUDE (CheckIncludeFiles)
 INCLUDE (CheckFunctionExists)
 
 CHECK_INCLUDE_FILES (security/pam_appl.h HAVE_PAM_APPL_H)
+CHECK_INCLUDE_FILES (security/pam_ext.h HAVE_PAM_EXT_H)
 CHECK_FUNCTION_EXISTS (strndup HAVE_STRNDUP)
 
 IF(HAVE_PAM_APPL_H)
@@ -21,7 +22,7 @@ IF(HAVE_PAM_APPL_H)
                      WORKING_DIRECTORY \$ENV{DESTDIR}\${CMAKE_INSTALL_PREFIX}/${INSTALL_PLUGINDIR}/)"
                    COMPONENT Server)
   ENDIF()
-  IF(TARGET auth_pam OR TARGET auth_pam_v1)
+  IF(HAVE_PAM_EXT_H AND (TARGET auth_pam OR TARGET auth_pam_v1))
     ADD_SUBDIRECTORY(testing)
     ADD_LIBRARY(pam_user_map MODULE mapper/pam_user_map.c)
     TARGET_LINK_LIBRARIES(pam_user_map pam)
