Clarify the meaning of a test.

Rather than using err() if either of two failure conditions
fires (which can produce spurious error messages), just use
errx() if the one condition that really matters fires.

In practice, this single test is enough to detect the failure
mode we're looking for (kqueue being inherited across fork).

Approved by: mentor (rwatson), re (Capsicum blanket)
Sponsored by: Google Inc

tools/regression/kqueue/config.h

@@ -1,4 +1,4 @@
-# $FreeBSD$
+/* $FreeBSD$ */
 
 #define HAVE_ERR_H 1
 #define HAVE_SYS_EVENT_H 1

tools/regression/kqueue/proc.c

@@ -43,9 +43,9 @@ add_and_delete(void)
     pid = fork();
     if (pid == 0) {
         struct stat s;
-        if ((fstat(kqfd, &s) != -1) || (errno != EBADF))
-            err(1, "%s:%d - %s: fstat(kqfd) in child did not return EBADF",
-                __FILE__, __LINE__, __func__);
+        if (fstat(kqfd, &s) != -1)
+            errx(1, "kqueue inherited across fork! (%s() at %s:%d)",
+	        __func__, __FILE__, __LINE__);
 
         pause();
         exit(2);