Be paranoid about multiple inclusions (apparently some systems don't like

it for certain header files.)  Be a little bit more careful in setting
up the standard environment in config.h.  This is AIX portability work.

config.h

@@ -70,7 +70,24 @@
 #include <unistd.h>
 #endif
 
+#ifdef HAVE_SETJMP_H
 #include <setjmp.h>
+#endif
+
+#ifdef TIME_WITH_SYS_TIME
+#include <sys/time.h>
+#include <time.h>
+#else
+#if HAVE_SYS_TIME_H
+#include <sys/time.h>
+#else
+#include <time.h>
+#endif
+#endif
+
+#include <errno.h>
+#include <signal.h>
+
 #include <sys/socket.h>
 
 /* If we don't have intmax_t, try creating it */