UBUNTU: [Packaging] force creation of headers directory

UBUNTU: [Packaging] force creation of headers directory

BugLink: https://bugs.launchpad.net/bugs/1847969
Due to a race condition, some times the headers directory already
exists when running the install-arch-headers rule. Make sure we do
not fail in that case.

Signed-off-by: Alfonso Sánchez-Beato <alfonso.sanchez-beato@canonical.com>
Signed-off-by: Shrirang Bagul <shrirang.bagul@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>