Add an option `--asume-packages-installed` to not try to install packages.

This is different than `--dont-install-packages` that will try to
compile the dependencies.

`--asumme-packages-installed` will no try to install packages, but will
not try either to compile dependencies.

kiwixbuild/__init__.py

@@ -38,6 +38,8 @@ def parse_args():
                           help="Clean all intermediate files after the (successfull) build")
     subgroup.add_argument('--dont-install-packages', action='store_true',
                           help="Do not try to install packages before compiling")
+    subgroup.add_argument('--assume-packages-installed', action='store_true',
+                          help="Assume the package to install to be aleady installed")
     subgroup.add_argument('--android-arch', action='append',
                           help=("Specify the architecture to build for android application/libraries.\n"
                                 "Can be specified several times to build for several architectures.\n"

kiwixbuild/builder.py

@@ -149,6 +149,10 @@ class Builder:
         packages_to_have = self._get_packages()
         packages_to_have = remove_duplicates(packages_to_have)
 
+        if option('assume_packages_installed'):
+            print("SKIP, Assume package installed")
+            return
+
         distname = neutralEnv('distname')
         if distname in ('fedora', 'redhat', 'centos'):
             package_installer = 'sudo dnf install {}'

travis/compile_all.py

@@ -75,6 +75,8 @@ def run_kiwix_build(target, platform,
     command = ['kiwix-build']
     command.append(target)
     command.append('--hide-progress')
+    if platform == 'flatpak':
+        command.append('--assume-packages-installed')
     if target == 'kiwix-android' and platform.startswith('android_'):
         command.extend(['--target-platform', 'android', '--android-arch', platform[8:]])
     elif platform == 'android':