diff to get busybox 1.13 stable building on my Ubuntu 64-bit 12.04 machine with gcc 4.8.

gistfile1.diff

diff --git a/include/libbb.h b/include/libbb.h
index 08fed90..ee166c2 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -89,6 +89,7 @@ int klogctl(int type, char *b, int len);
 char *dirname(char *path);
 /* Include our own copy of struct sysinfo to avoid binary compatibility
  * problems with Linux 2.4, which changed things.  Grumble, grumble. */
+#if 0
 struct sysinfo {
        long uptime;                    /* Seconds since boot */
        unsigned long loads[3];         /* 1, 5, and 15 minute load averages */
@@ -105,6 +106,10 @@ struct sysinfo {
        unsigned int mem_unit;          /* Memory unit size in bytes */
        char _f[20 - 2 * sizeof(long) - sizeof(int)]; /* Padding: libc5 uses this.. */
 };
+#else
+struct sysinfo;
+#endif
+
 int sysinfo(struct sysinfo* info);
 
 
diff --git a/init/init.c b/init/init.c
index 5536504..7f6beb2 100644
--- a/init/init.c
+++ b/init/init.c
@@ -13,6 +13,7 @@
 #include <syslog.h>
 #include <paths.h>
 #include <sys/reboot.h>
+#include <sys/sysinfo.h>
 
 /* Was a CONFIG_xxx option. A lot of people were building
  * not fully functional init by switching it on! */
diff --git a/procps/free.c b/procps/free.c
index e76dd21..d67244c 100644
--- a/procps/free.c
+++ b/procps/free.c
@@ -10,6 +10,7 @@
 /* getopt not needed */
 
 #include "libbb.h"
+#include <sys/sysinfo.h>
 
 int free_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int free_main(int argc, char **argv)
diff --git a/procps/uptime.c b/procps/uptime.c
index d9aa1d0..3e29c0c 100644
--- a/procps/uptime.c
+++ b/procps/uptime.c
@@ -16,6 +16,7 @@
 /* getopt not needed */
 
 #include "libbb.h"
+#include <sys/sysinfo.h>
 
 #ifndef FSHIFT
 # define FSHIFT 16              /* nr of bits of precision */