getaddrinfo: zero the hints structure

This silences the memory sanitizer. All fields were already correctly
initialized but the struct padding wasn't, causing an uninitialized read
warning.

Reviewed-by: Tim Hudson <tjh@openssl.org>

crypto/bio/b_addr.c

diff --git a/crypto/bio/b_addr.c b/crypto/bio/b_addr.c
index a46cf93..6125e86 100644
--- a/crypto/bio/b_addr.c
+++ b/crypto/bio/b_addr.c
@@ -681,18 +681,13 @@
         int gai_ret = 0;
 #ifdef AI_PASSIVE
         struct addrinfo hints;
+        memset(&hints, 0, sizeof hints);
 
-        hints.ai_flags = 0;
 # ifdef AI_ADDRCONFIG
         hints.ai_flags = AI_ADDRCONFIG;
 # endif
         hints.ai_family = family;
         hints.ai_socktype = socktype;
-        hints.ai_protocol = 0;
-        hints.ai_addrlen = 0;
-        hints.ai_addr = NULL;
-        hints.ai_canonname = NULL;
-        hints.ai_next = NULL;
 
         if (lookup_type == BIO_LOOKUP_SERVER)
             hints.ai_flags |= AI_PASSIVE;