scons: move to packages feed

This patch removes scons host build tool, as commit 7087efd72a8d
("scons: move host build tool to a proper place") in the packages feed
has moved scons into the new home.

There are currently no packages in the master tree which would need
scons, yet scons is build always as part of host tools, just in order to
satisfy host build dependency of few packages in the packages feeds.

Ref: https://github.com/openwrt/packages/pull/9584
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

tools/Makefile

@@ -25,7 +25,7 @@ tools-$(BUILD_TOOLCHAIN) += gmp mpfr mpc libelf expat
 tools-y += m4 libtool autoconf automake flex bison pkg-config mklibs zlib
 tools-y += sstrip make-ext4fs e2fsprogs mtd-utils mkimage
 tools-y += firmware-utils patch-image quilt padjffs2
-tools-y += mm-macros missing-macros cmake scons bc findutils gengetopt patchelf
+tools-y += mm-macros missing-macros cmake bc findutils gengetopt patchelf
 tools-y += mtools dosfstools libressl
 tools-$(CONFIG_TARGET_orion_generic) += wrt350nv2-builder upslug2
 tools-$(CONFIG_TARGET_x86) += qemu