Add infrastructure for ecdsa_verify_restartable()

library/ecp.c

@@ -100,6 +100,14 @@ void mbedtls_ecp_set_max_ops( unsigned max_ops )
     ecp_max_ops = max_ops;
 }
 
+/*
+ * Check if restart is enabled
+ */
+int mbedtls_ecp_restart_enabled( void )
+{
+    return( ecp_max_ops != 0 );
+}
+
 /*
  * Restart sub-context for ecp_mul_comb()
  */