Revert "tools/upx: remove (coolsnowwolf#10622)"

This reverts commit 71b4500.

tools/Makefile

@@ -25,7 +25,7 @@ tools-y += autoconf autoconf-archive automake bc bison cmake cpio dosfstools
 tools-y += e2fsprogs expat fakeroot findutils firmware-utils flex gengetopt
 tools-y += libressl libtool lzma m4 make-ext4fs meson missing-macros mkimage
 tools-y += mklibs mtd-utils mtools ninja padjffs2 patch-image
-tools-y += patchelf pkgconf quilt squashfskit4 sstrip zip zlib zstd
+tools-y += patchelf pkgconf quilt squashfskit4 sstrip ucl upx zip zlib zstd
 tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(BUILD_B43_TOOLS),y) += b43-tools
 tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(BUILD_ISL),y) += isl
 tools-$(if $(CONFIG_BUILD_ALL_HOST_TOOLS)$(BUILD_TOOLCHAIN),y) += gmp mpc mpfr
@@ -43,6 +43,7 @@ $(curdir)/autoconf/compile := $(curdir)/m4/compile
 $(curdir)/automake/compile := $(curdir)/autoconf/compile $(curdir)/pkgconf/compile $(curdir)/xz/compile
 $(curdir)/b43-tools/compile := $(curdir)/bison/compile
 $(curdir)/bc/compile := $(curdir)/bison/compile $(curdir)/libtool/compile
+$(curdir)/upx/compile := $(curdir)/ucl/compile
 $(curdir)/bison/compile := $(curdir)/flex/compile
 $(curdir)/cbootimage/compile += $(curdir)/automake/compile
 $(curdir)/cmake/compile += $(curdir)/libressl/compile $(curdir)/ninja/compile $(curdir)/expat/compile $(curdir)/xz/compile $(curdir)/zlib/compile $(curdir)/zstd/compile

tools/ucl/Makefile

@@ -0,0 +1,49 @@
+#
+# Copyright (C) 2021 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=ucl
+PKG_VERSION:=1.03
+
+PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
+PKG_SOURCE_URL:=http://www.oberhumer.com/opensource/ucl/download/$(PKG_SOURCE)
+PKG_HASH:=b865299ffd45d73412293369c9754b07637680e5c826915f097577cd27350348
+
+HOST_BUILD_DIR:=$(BUILD_DIR_HOST)/$(PKG_NAME)-$(PKG_VERSION)
+
+include $(INCLUDE_DIR)/host-build.mk
+
+HOST_CFLAGS +=-std=gnu89 -std=c90 -fPIC -Wno-error=implicit-function-declaration
+HOST_CFLAGS +=-std=gnu89
+
+define Host/Prepare
+	$(Host/Prepare/Default)
+	mkdir -p $(STAGING_DIR_HOST)/include/ucl
+endef
+
+define Host/Configure
+	(cd $(HOST_BUILD_DIR); \
+	CC="$(HOSTCC)" \
+	CFLAGS="$(HOST_CFLAGS)" \
+	./configure --prefix=$(STAGING_DIR_HOST) \
+	);
+	$(call Host/Configure/Default)
+endef
+
+define Host/Compile
+	$(MAKE) -C $(HOST_BUILD_DIR)
+endef
+
+define Host/Install
+	$(MAKE) -C $(HOST_BUILD_DIR) install
+endef
+
+define Host/Clean
+	rm -rf $(STAGING_DIR_HOST)/include/ucl
+endef
+
+$(eval $(call HostBuild))