cyassl: Use error-ssl.h when available

Versions since at least 2.9.4 renamed error.h to error-ssl.h, so use
whichever one is available.

configure.ac

@@ -2003,6 +2003,9 @@ if test "$curl_ssl_msg" = "$init_ssl_msg"; then
       dnl cyassl/ctaocrypt/types.h needs SIZEOF_LONG_LONG defined!
       AC_CHECK_SIZEOF(long long)
 
+      dnl Versions since at least 2.9.4 renamed error.h to error-ssl.h
+      AC_CHECK_HEADERS(cyassl/error-ssl.h)
+
       LIBS="-lcyassl -lm $LIBS"
 
       if test -n "$cyassllib"; then

lib/vtls/cyassl.c

@@ -47,11 +47,16 @@
 #define _MPRINTF_REPLACE /* use our functions only */
 #include <curl/mprintf.h>
 #include "curl_memory.h"
+
+#include <cyassl/ssl.h>
+#ifdef HAVE_CYASSL_ERROR_SSL_H
+#include <cyassl/error-ssl.h>
+#else
+#include <cyassl/error.h>
+#endif
+
 /* The last #include file should be: */
 #include "memdebug.h"
-#include <cyassl/ssl.h>
-#include <cyassl/error.h>
-
 
 static Curl_recv cyassl_recv;
 static Curl_send cyassl_send;