android: Add button to open privacy URL

In the About dialog, add a "Privacy Policy"
button when a privacy URL is set, i.e.
the `--with-privacy-policy-url=<URL>` autogen
option is used.
Clicking the button will fire an Intent
to open that URL.

Use a custom build config field as described at [1]
to make the privacy policy URL available to
the Java code.

[1] https://developer.android.com/build/gradle-tips#share-custom-fields-and-resource-values-with-your-app-code

Change-Id: I6e1a9aff885e4ce132284f49e722b3343fc51b79
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/159445
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

0 files changed, 0 insertions, 0 deletions