openssl: move engine.mk to INCLUDE_DIR

engine.mk is supposed to be included by engine packages, but it will not
be present in the SDK in the same place as in the main repository.

Move it to include/openssl-engine.mk to avoid this.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

include/openssl-engine.mk

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright (C) 2022 Enéas Ulir de Queiroz
+
+ENGINES_DIR=engines-1.1
+
+define Package/openssl/engine/Default
+  SECTION:=libs
+  CATEGORY:=Libraries
+  SUBMENU:=SSL
+  DEPENDS:=libopenssl @OPENSSL_ENGINE +libopenssl-conf
+endef
+
+# 1 = engine name
+# 2 - package name, defaults to libopenssl-$(1)
+define Package/openssl/add-engine
+  OSSL_ENG_PKG:=$(if $(2),$(2),libopenssl-$(1))
+  Package/$$(OSSL_ENG_PKG)/conffiles:=/etc/ssl/engines.cnf.d/$(1).cnf
+
+  define Package/$$(OSSL_ENG_PKG)/install
+	$$(INSTALL_DIR)  $$(1)/usr/lib/$(ENGINES_DIR)
+	$$(INSTALL_BIN)  $$(PKG_INSTALL_DIR)/usr/lib/$(ENGINES_DIR)/$(1).so \
+			 $$(1)/usr/lib/$(ENGINES_DIR)
+	$$(INSTALL_DIR)  $$(1)/etc/ssl/engines.cnf.d
+	$$(INSTALL_DATA) ./files/$(1).cnf $$(1)/etc/ssl/engines.cnf.d/
+  endef
+
+  define Package/$$(OSSL_ENG_PKG)/postinst :=
+#!/bin/sh
+OPENSSL_UCI="$$$${IPKG_INSTROOT}/etc/config/openssl"
+
+[ -z "$$$${IPKG_INSTROOT}" ] && uci -q get openssl.$(1) >/dev/null && exit 0
+
+cat << EOF >> "$$$${OPENSSL_UCI}"
+
+config engine '$(1)'
+	option enabled '1'
+EOF
+
+[ -n "$$$${IPKG_INSTROOT}" ] || /etc/init.d/openssl reload
+  endef
+
+  define Package/$$(OSSL_ENG_PKG)/postrm :=
+#!/bin/sh
+[ -n "$$$${IPKG_INSTROOT}" ] && exit 0
+uci delete openssl.$(1)
+uci commit openssl
+/etc/init.d/openssl reload
+  endef
+endef