PORTAGE_XATTR_EXCLUDE: add common user.* attributes (bug 640290)

Common user.* attributes should be safe to exclude, and they
are not supported on tmpfs, except for user.pax.* attributes
that are supported with the patch from bug 470644.

See: https://www.freedesktop.org/wiki/CommonExtendedAttributes/
Bug: https://bugs.gentoo.org/612612
Bug: https://bugs.gentoo.org/640290
diff --git a/cnf/make.globals b/cnf/make.globals
index ea50ab6..08a37a5 100644
--- a/cnf/make.globals
+++ b/cnf/make.globals
@@ -127,8 +127,11 @@
 # security.* attributes may be special (see bug 461868), but
 # security.capability is specifically not excluded (bug 548516).
 # system.nfs4_acl attributes are irrelevant, see bug #475496.
+# user.* attributes are not supported on tmpfs (bug 640290), but
+# user.pax.* is supported with the patch from bug 470644.
 PORTAGE_XATTR_EXCLUDE="btrfs.* security.evm security.ima
-	security.selinux system.nfs4_acl"
+	security.selinux system.nfs4_acl user.apache_handler
+	user.Beagle.* user.dublincore.* user.mime_encoding user.xdg.*"
 
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