Add infrastructure for ecdsa_verify_restartable()
diff --git a/include/mbedtls/ecdsa.h b/include/mbedtls/ecdsa.h
index c7b9f27..d2f83b2 100644
--- a/include/mbedtls/ecdsa.h
+++ b/include/mbedtls/ecdsa.h
@@ -58,11 +58,19 @@
 #if defined(MBEDTLS_ECP_RESTARTABLE)
 
 /**
+ * \brief           Internal restart context for ecdsa_verify()
+ *
+ * \note            Opaque struct
+ */
+typedef struct mbedtls_ecdsa_restart_ver mbedtls_ecdsa_restart_ver_ctx;
+
+/**
  * \brief           General context for resuming ECDSA operations
  */
 typedef struct
 {
     mbedtls_ecp_restart_ctx ecp;        /*!<  base context (admin+ecp info) */
+    mbedtls_ecdsa_restart_ver_ctx *ver; /*!<  ecdsa_verify() sub-context    */
 } mbedtls_ecdsa_restart_ctx;
 
 #else /* MBEDTLS_ECP_RESTARTABLE */