overlay profiles: Some cleanups

Mask split-usr globally, not only for generic images. Move some SDK
only USE flags to SDK target profile (cros_host, expat). Drop
duplicated disabling of cups USE flag.

sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/make.defaults

@@ -8,8 +8,7 @@ USE_EXPAND="${USE_EXPAND} TESTS"
 # For now this is only informational and set by coreos-go.eclass
 USE_EXPAND="${USE_EXPAND} GO_VERSION"
 
-# Extra use flags for CoreOS SDK
-USE="${USE} cros_host expat -cracklib -introspection -cups -tcpd -berkdb"
+USE="${USE} -cracklib -introspection -cups -tcpd -berkdb"
 
 # Use Python 3 as the default version
 USE="${USE} -python_single_target_python2_7 python_single_target_python3_11"

sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/generic/use.force → sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/use.force

@@ -1,4 +1,7 @@
 # We don't have a separate /{bin,lib} and /usr/{bin,lib}. But the base
 # profile in portage-stable forces split-usr, so here we unforce it
 # and in use.mask we mask it.
+#
+# TODO: Drop it when we move to
+# default/linux/{amd64,arm64}/23.0/hardened/selinux/systemd profile
 -split-usr

sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/use.mask

@@ -21,3 +21,11 @@ python_single_target_python3_13
 # We don't care about i10n, takes too much space, pulls in too many
 # extra dependencies.
 nls
+
+# We don't have a separate /{bin,lib} and /usr/{bin,lib}. But the base
+# profile in portage-stable forces split-usr, so in use.force we
+# unforce it and here we mask it.
+#
+# TODO: Drop it when we move to
+# default/linux/{amd64,arm64}/23.0/hardened/selinux/systemd profile
+split-usr

sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/generic/make.defaults

@@ -2,9 +2,9 @@
 # Distributed under the terms of the GNU General Public License v2
 
 USE="acpi usb cryptsetup policykit"
-USE="${USE} -split-usr -cros_host -expat -cairo -X -man"
+USE="${USE} -cros_host -expat -cairo -X -man"
 USE="${USE} -acl -gpm -python"
-USE="${USE} -fortran -abiword -perl -cups -poppler-data"
+USE="${USE} -fortran -abiword -perl -poppler-data"
 
 # Exclude documentation
 FEATURES="nodoc noinfo noman"

sdk_container/src/third_party/coreos-overlay/profiles/coreos/targets/sdk/make.defaults

@@ -1,4 +1,4 @@
-USE="man -pam"
+USE="cros_host expat man -pam"
 
 # Used by some old goo in profiles/coreos/base/profile.bashrc
 # TODO: clean up that old goo