openssl: fix arch handling

Closes #497

Use ARCH instead of BR2_ARCH as BR2_ARCH won't match because of the
surrounding quotes.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
diff --git a/CHANGES b/CHANGES
index 77c4398..c1bfe38 100644
--- a/CHANGES
+++ b/CHANGES
@@ -46,6 +46,7 @@
 	#451: Upgrade from unmaintained dosfstools-2.11 to dosfstools-3.0.3
 	#467: DirectFB 1.4.1
 	#473: memstat_0.5.tar.gz has install with -D and that fails "make"
+	#497: OpenSSL RSA key generation hangs on x86_64
 
 2009.05, Released June 1st, 2009: