Include switch for proxy types (#105)

Co-authored-by: Ryan Carper <51676630+rccarper@users.noreply.github.com>

Author: bretambrose

source/s3_client.c

@@ -20,6 +20,7 @@
 #include <aws/common/system_info.h>
 #include <aws/http/connection.h>
 #include <aws/http/connection_manager.h>
+#include <aws/http/proxy.h>
 #include <aws/http/request_response.h>
 #include <aws/io/channel_bootstrap.h>
 #include <aws/io/event_loop.h>