Revert "sys-libs/readline: Mark 8.0 stable."

This reverts commit 13c55173273a77dce8897b52eef8d2ee81338a7d.

Reason for revert: Errors entering chroot.

Original change's description:
> sys-libs/readline: Mark 8.0 stable.
>
> BUG=chromium:1117585
> TEST=CQ passes
>
> Change-Id: Ic2dc006fee419376a27f4c05ee26e9da216e2353
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2490409
> Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
> Reviewed-by: Navil Perez <navil@google.com>
> Tested-by: Navil Perez <navil@google.com>

Bug: chromium:1143738
Change-Id: I7d177b63ff1785087d74292f277de86f38c312a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2506959
Reviewed-by: Navil Perez <navil@google.com>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Tested-by: Navil Perez <navil@google.com>
diff --git a/sys-libs/readline/readline-8.0_p4.ebuild b/sys-libs/readline/readline-8.0_p4.ebuild
index 2978d11..530bd1c 100644
--- a/sys-libs/readline/readline-8.0_p4.ebuild
+++ b/sys-libs/readline/readline-8.0_p4.ebuild
@@ -41,7 +41,7 @@
 
 LICENSE="GPL-3"
 SLOT="0/8"  # subslot matches SONAME major
-KEYWORDS="*"
+KEYWORDS="~*"
 IUSE="static-libs +unicode utils"
 
 RDEPEND=">=sys-libs/ncurses-5.9-r3:0=[static-libs?,unicode?,${MULTILIB_USEDEP}]"