tools/kwbimage: Support building with LibreSSL

The kwbimage utility fails to compile when LibreSSL is present on
the host system instead of OpenSSL. This one-line patch resolves
this.
Signed-off-by: NMarek Behun <marek.behun@nic.cz>

tools/kwbimage.c

@@ -24,7 +24,7 @@
 #include <openssl/err.h>
 #include <openssl/evp.h>
 
-#if OPENSSL_VERSION_NUMBER < 0x10100000L
+#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
 static void RSA_get0_key(const RSA *r,
                  const BIGNUM **n, const BIGNUM **e, const BIGNUM **d)
 {