TBB: build 'cert_create' with ECDSA only if OpenSSL supports it

Some Linux distributions include an OpenSSL library which has been
built without ECDSA support. Trying to build the certificate
generation tool on those distributions will result in a build error.

This patch fixes that issue by including ECDSA support only if
OpenSSL has been built with ECDSA. In that case, the OpenSSL
configuration file does not define the OPENSSL_NO_EC macro. The tool
will build successfully, although the resulting binary will not
support ECDSA keys.

Change-Id: I4627d1abd19eef7ad3251997d8218599187eb902
diff --git a/tools/cert_create/include/key.h b/tools/cert_create/include/key.h
index dfb3150..165ffa1 100644
--- a/tools/cert_create/include/key.h
+++ b/tools/cert_create/include/key.h
@@ -47,7 +47,10 @@
 /* Supported key algorithms */
 enum {
 	KEY_ALG_RSA,
-	KEY_ALG_ECDSA
+#ifndef OPENSSL_NO_EC
+	KEY_ALG_ECDSA,
+#endif /* OPENSSL_NO_EC */
+	KEY_ALG_MAX_NUM
 };
 
 /*