Use an explicit name for the struct for definition of RAW_EXTENSION

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>

ssl/ssl_locl.h

diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index 8f7f930..79f47fc 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -1624,7 +1624,7 @@
 } SSL3_COMP;
 # endif
 
-typedef struct {
+typedef struct raw_extension_st {
     unsigned int type;
     PACKET data;
 } RAW_EXTENSION;