Add org.apertis.demo.curl app

Create flatpak package for `curl`.
Add some of the libraries to the runtime to exercise ability for a package
to use libraries from runtime and app packages.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

apps/org.apertis.demo.curl.yaml

+---
+id: org.apertis.demo.curl
+branch: v2021dev1
+runtime: org.apertis.demo.Platform
+runtime-version: v2021dev1
+sdk: org.apertis.demo.Sdk
+command: curl
+modules:
+  - name: curl
+    x-flatdeb-apt-packages:
+      - curl
+    sources:
+      - type: file
+        path: deb-buildapi/configure
+        dest: '.'
+      - type: file
+        path: deb-buildapi/Makefile
+...

deb-buildapi/Makefile

+all:
+	if ! [ -d /var/lib/dpkg ]; then \
+		cp -PRp /usr/var /; \
+	fi
+	set -e; \
+	if test -d src; then \
+		cd src && \
+		dpkg-buildpackage -b -nc -d \
+		--build-profiles=pkg.flatpak.app,nocheck,nodoc; \
+	fi; \
+
+# This assumes we don't need to run maintainer scripts.
+install:
+	set -e; \
+	for deb in *.deb; do \
+		dpkg-deb --fsys-tarfile "$$deb" | \
+		tar -xf- -C /app \
+		--transform='s,^(\.?/)?(app|usr)/,,x'; \
+	done

deb-buildapi/configure

+#!/bin/sh
+
+if [ ! -e Makefile ]; then
+	cp "$(dirname "$0")/Makefile" Makefile
+fi
+
+exit 0

runtimes/org.apertis.demo.yaml

 ---
 id_prefix: org.apertis.demo
 
+add_packages:
+  - libicu63
+  - libldap-2.4-2
+
 add_packages_multiarch:
   - libc6
   - libstdc++6