[BUILD] fix build on FreeBSD for INT_MIN/INT_MAX

FreeBSD stores INT_MIN and INT_MAX in sys/limits.h only. Other systems
(Solaris) have it in sys/types.h and do not have sys/limits.h. Let's
include sys/limits.h only if INT_MAX is not defined.
diff --git a/include/common/standard.h b/include/common/standard.h
index 5b9d4a8..3dea1fd 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -22,10 +22,16 @@
 #ifndef _COMMON_STANDARD_H
 #define _COMMON_STANDARD_H
 
+#include <sys/types.h>
 #include <netinet/in.h>
 #include <common/config.h>
 #include <proto/fd.h>
 
+#ifndef INT_MAX
+/* Needed on FreeBSD */
+#include <sys/limits.h>
+#endif
+
 /****** string-specific macros and functions ******/
 /* if a > max, then bound <a> to <max>. The macro returns the new <a> */
 #define UBOUND(a, max)	({ typeof(a) b = (max); if ((a) > b) (a) = b; (a); })