Bump the pbuild data size limit to 7G; Firefox 74 no longer builds in 6G.

ok deraadt@

src/etc/etc.amd64/login.conf

@@ -1,4 +1,4 @@
-# $OpenBSD: login.conf,v 1.13 2019/11/05 19:03:46 solene Exp $
+# $OpenBSD: login.conf,v 1.14 2020/03/11 15:41:48 naddy Exp $
 
 #
 # Sample login.conf file.  See login.conf(5) for details.
@@ -92,7 +92,7 @@ authpf:\
 #
 pbuild:\
 	:datasize-max=infinity:\
-	:datasize-cur=6144M:\
+	:datasize-cur=7168M:\
 	:maxproc-max=1024:\
 	:maxproc-cur=384:\
 	:priority=5:\