this is in line with 
http://bugs.php.net/version4/bugs.php?id=3147

but I cannot determine a way of adding information to an existing bug. 

Have this same problem under FreeBSD with the PHP4b4pl1 release.

Someone reported success with the following patch under linux, but I was unable to duplicate it.

Index: microtime.c
===================================================================
RCS file: /repository/php4/ext/standard/microtime.c,v
retrieving revision 1.15
diff -u -u -r1.15 microtime.c
--- microtime.c	2000/02/19 23:41:21	1.15
+++ microtime.c	2000/02/23 02:39:02
@@ -22,6 +22,8 @@
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+#include <sys/resource.h>
+#include <unistd.h>
 #include <string.h>
 #include <errno.h>
 
@@ -90,6 +92,7 @@
    returns an array of usage statistics */
 PHP_FUNCTION(getrusage)
 {
+#define HAVE_GETRUSAGE 1
 #if HAVE_GETRUSAGE
 	struct rusage usg;
 	int ac = ARG_COUNT(ht);