Update from 1.0.0-stable.

crypto/bio/bss_dgram.c

diff --git a/crypto/bio/bss_dgram.c b/crypto/bio/bss_dgram.c
index 80d31b1..2e1a6fa 100644
--- a/crypto/bio/bss_dgram.c
+++ b/crypto/bio/bss_dgram.c
@@ -333,8 +333,10 @@
 	int *ip;
 	struct sockaddr *to = NULL;
 	bio_dgram_data *data = NULL;
+#if defined(IP_MTU_DISCOVER) || defined(IP_MTU)
 	long sockopt_val = 0;
 	unsigned int sockopt_len = 0;
+#endif
 #ifdef OPENSSL_SYS_LINUX
 	socklen_t addr_len;
 	struct sockaddr_storage addr;