Bump datasize-cur to 4Gb for pbuild class on sparc64, rust is a pig.

ok semarie@

src/etc/etc.sparc64/login.conf

@@ -1,4 +1,4 @@
-# $OpenBSD: login.conf,v 1.10 2019/06/02 06:46:18 jmc Exp $
+# $OpenBSD: login.conf,v 1.11 2019/09/08 16:57:17 landry Exp $
 
 #
 # Sample login.conf file.  See login.conf(5) for details.
@@ -92,7 +92,7 @@ authpf:\
 #
 pbuild:\
 	:datasize-max=infinity:\
-	:datasize-cur=2048M:\
+	:datasize-cur=4096M:\
 	:maxproc-max=1024:\
 	:maxproc-cur=256:\
 	:tc=default: