Fix gcc-7 warnings.
- Mostly missing fall thru comments
- And uninitialized value used in sslapitest.c

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3440)
diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index b9b8da1..e6a0b35 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -517,7 +517,8 @@
              */
             return WRITE_TRAN_FINISHED;
         }
-        /* Renegotiation - fall through */
+        /* Renegotiation */
+        /* fall thru */
     case TLS_ST_BEFORE:
         st->hand_state = TLS_ST_CW_CLNT_HELLO;
         return WRITE_TRAN_CONTINUE;
diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c
index d37cbc3..5c00b0a 100644
--- a/ssl/statem/statem_lib.c
+++ b/ssl/statem/statem_lib.c
@@ -1616,6 +1616,7 @@
          * Fall through if we are TLSv1.3 already (this means we must be after
          * a HelloRetryRequest
          */
+        /* fall thru */
     case TLS_ANY_VERSION:
         table = tls_version_table;
         break;