Style: added missing "static" specifiers.

Mostly found by gcc -Wtraditional, per "non-static declaration of ...
follows static declaration [-Wtraditional]" warnings.

src/event/ngx_event_openssl.c

diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
index fb08230..d4ba1f7 100644
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -2767,7 +2767,7 @@
 
 #ifdef SSL_READ_EARLY_DATA_SUCCESS
 
-ssize_t
+static ssize_t
 ngx_ssl_write_early(ngx_connection_t *c, u_char *data, size_t size)
 {
     int        n, sslerr;

src/stream/ngx_stream_ssl_module.c

diff --git a/src/stream/ngx_stream_ssl_module.c b/src/stream/ngx_stream_ssl_module.c
index 4b6926a..530fe8b 100644
--- a/src/stream/ngx_stream_ssl_module.c
+++ b/src/stream/ngx_stream_ssl_module.c
@@ -23,7 +23,8 @@
     ngx_connection_t *c);
 static void ngx_stream_ssl_handshake_handler(ngx_connection_t *c);
 #ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
-int ngx_stream_ssl_servername(ngx_ssl_conn_t *ssl_conn, int *ad, void *arg);
+static int ngx_stream_ssl_servername(ngx_ssl_conn_t *ssl_conn, int *ad,
+    void *arg);
 #endif
 #ifdef TLSEXT_TYPE_application_layer_protocol_negotiation
 static int ngx_stream_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn,
@@ -451,7 +452,7 @@
 
 #ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
 
-int
+static int
 ngx_stream_ssl_servername(ngx_ssl_conn_t *ssl_conn, int *ad, void *arg)
 {
     return SSL_TLSEXT_ERR_OK;
@@ -502,7 +503,7 @@
 
 #ifdef SSL_R_CERT_CB_ERROR
 
-int
+static int
 ngx_stream_ssl_certificate(ngx_ssl_conn_t *ssl_conn, void *arg)
 {
     ngx_str_t                    cert, key;