libressl: bump to 2.6.4

Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libressl/libressl.hash

@@ -1,2 +1,2 @@
 # From https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/SHA256
-sha256	aead6598263171b96970da0d881e616d0813b69b35ebdc5991f87ff2ea7f5c98	libressl-2.6.3.tar.gz
+sha256	638a20c2f9e99ee283a841cd787ab4d846d1880e180c4e96904fc327d419d11f	libressl-2.6.4.tar.gz

package/libressl/libressl.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBRESSL_VERSION = 2.6.3
+LIBRESSL_VERSION = 2.6.4
 LIBRESSL_SITE = https://ftp.openbsd.org/pub/OpenBSD/LibreSSL
 LIBRESSL_LICENSE = ISC (new additions), OpenSSL or SSLeay (original OpenSSL code)
 LIBRESSL_LICENSE_FILES = COPYING