RT3684: rand_egd needs stddef.h

And remove backup definition of offsetof.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

crypto/rand/rand_egd.c

@@ -113,6 +113,7 @@ int RAND_egd_bytes(const char *path, int bytes)
 #else
 # include <openssl/opensslconf.h>
 # include OPENSSL_UNISTD
+# include <stddef.h>
 # include <sys/types.h>
 # include <sys/socket.h>
 # ifndef NO_SYS_UN_H
@@ -130,10 +131,6 @@ struct sockaddr_un {
 # include <string.h>
 # include <errno.h>
 
-# ifndef offsetof
-#  define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
-# endif
-
 int RAND_query_egd_bytes(const char *path, unsigned char *buf, int bytes)
 {
     int ret = 0;