Conditionally compile per innetgr availability

innetgr is not available/functional in uclibc, provide conditions for compilation.

Signed-off-by: Dmitry Golubovsky <golubovsky@gmail.com>

Index: linux-pam-1.1.4/modules/pam_time/pam_time.c
============================================================================
--- linux-pam-1.1.4/modules/pam_time/pam_time.c	2011-06-21 05:04:56.000000000 -0400
+++ linux-pam-1.1.4/modules/pam_time/pam_time.c	2012-08-09 21:02:29.000000000 -0400
@@ -554,8 +554,14 @@
 	       continue;
 	  }
 	  /* If buffer starts with @, we are using netgroups */
-	  if (buffer[0] == '@')
+	  if (buffer[0] == '@') {
+#ifdef HAVE_INNETGR
 	    good &= innetgr (&buffer[1], NULL, user, NULL);
+#else
+	    good = 0;
+	    pam_syslog (pamh, LOG_ERR, "pam_time does not have netgroup support");
+#endif /* HAVE_INNETGR */
+	  }
 	  else
 	    good &= logic_field(pamh, user, buffer, count, is_same);
 	  D(("with user: %s", good ? "passes":"fails" ));
