Split extensions code into core extensions and server extensions code

Later we will have client extensions code too.

Perl changes reviewed by Richard Levitte. Non-perl changes reviewed by Rich
Salz
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>

ssl/build.info

@@ -2,7 +2,8 @@ LIBS=../libssl
 SOURCE[../libssl]=\
         pqueue.c packet.c \
         statem/statem_srvr.c statem/statem_clnt.c  s3_lib.c  s3_enc.c record/rec_layer_s3.c \
-        statem/statem_lib.c statem/extensions.c s3_cbc.c s3_msg.c \
+        statem/statem_lib.c statem/extensions.c statem/extensions_srvr.c \
+        s3_cbc.c s3_msg.c \
         methods.c   t1_lib.c  t1_enc.c tls13_enc.c t1_ext.c \
         d1_lib.c  record/rec_layer_d1.c d1_msg.c \
         statem/statem_dtls.c d1_srtp.c \

ssl/statem/statem_locl.h

@@ -155,3 +155,27 @@ __owur int tls_parse_extension(SSL *s, int type, int context, RAW_EXTENSION *ext
                                size_t numexts, int *al);
 __owur int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                                     int *al);
+
+/* Server Extension processing */
+int tls_parse_clienthello_renegotiate(SSL *s, PACKET *pkt, int *al);
+int tls_parse_clienthello_server_name(SSL *s, PACKET *pkt, int *al);
+#ifndef OPENSSL_NO_SRP
+int tls_parse_clienthello_srp(SSL *s, PACKET *pkt, int *al);
+#endif
+#ifndef OPENSSL_NO_EC
+int tls_parse_clienthello_ec_pt_formats(SSL *s, PACKET *pkt, int *al);
+int tls_parse_clienthello_supported_groups(SSL *s, PACKET *pkt, int *al);
+#endif
+int tls_parse_clienthello_session_ticket(SSL *s, PACKET *pkt, int *al);
+int tls_parse_clienthello_sig_algs(SSL *s, PACKET *pkt, int *al);
+int tls_parse_clienthello_status_request(SSL *s, PACKET *pkt, int *al);
+#ifndef OPENSSL_NO_NEXTPROTONEG
+int tls_parse_clienthello_npn(SSL *s, PACKET *pkt, int *al);
+#endif
+int tls_parse_clienthello_alpn(SSL *s, PACKET *pkt, int *al);
+#ifndef OPENSSL_NO_SRTP
+int tls_parse_clienthello_use_srtp(SSL *s, PACKET *pkt, int *al);
+#endif
+int tls_parse_clienthello_etm(SSL *s, PACKET *pkt, int *al);
+int tls_parse_clienthello_key_share(SSL *s, PACKET *pkt, int *al);
+int tls_parse_clienthello_ems(SSL *s, PACKET *pkt, int *al);