civetweb.c: change some local functions to static

Fix for cgcc warning:

src/civetweb.c:6189:22: warning: symbol 'mg_connect' was not declared.
  Should it be static?

src/civetweb.c:6743:6: warning: symbol 'get_system_name' was not declared.
 Should it be static?

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>

src/civetweb.c

@@ -6186,7 +6186,7 @@ void mg_close_connection(struct mg_connection *conn)
     mg_free(conn);
 }
 
-struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
+static struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
                                  char *ebuf, size_t ebuf_len)
 {
     static struct mg_context fake_ctx;
@@ -6740,7 +6740,7 @@ void mg_stop(struct mg_context *ctx)
 #endif /* _WIN32 && !__SYMBIAN32__ */
 }
 
-void get_system_name(char **sysName)
+static void get_system_name(char **sysName)
 {
 #if defined(_WIN32)
 #if !defined(__SYMBIAN32__)