mbedtls_ssl_handshake_params: move ecrs_ctx back further

"mbedtls_ssl_handshake_params: reorder fields to save code size" moved this
filed earlier along with byte-sized fields that should be in the 128-element
access window on Arm Thumb. This took away precious room in the 128-byte
window. Move it back further out.

Results (same architecture, config-suite-b.h + MBEDTLS_ECDH_LEGACY_CONTEXT +
MBEDTLS_ECP_RESTARTABLE):
library/ssl_cli.o: 2860 -> 2816 (diff: 44)
library/ssl_msg.o: 3080 -> 3076 (diff: 4)
library/ssl_srv.o: 3340 -> 3300 (diff: 40)
library/ssl_tls.o: 6546 -> 6478 (diff: 68)

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/ssl_misc.h

@@ -558,7 +558,6 @@ struct mbedtls_ssl_handshake_params
 
 #if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
     uint8_t ecrs_enabled;               /*!< Handshake supports EC restart? */
-    mbedtls_x509_crt_restart_ctx ecrs_ctx;  /*!< restart context            */
     enum { /* this complements ssl->state with info on intra-state operations */
         ssl_ecrs_none = 0,              /*!< nothing going on (yet)         */
         ssl_ecrs_crt_verify,            /*!< Certificate: crt_verify()      */
@@ -637,6 +636,10 @@ struct mbedtls_ssl_handshake_params
     size_t psk_len;                     /*!<  Length of PSK from callback   */
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+    mbedtls_x509_crt_restart_ctx ecrs_ctx;  /*!< restart context            */
+#endif
+
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
     mbedtls_ssl_key_cert *key_cert;     /*!< chosen key/cert pair (server)  */
 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)