This fixes the following lintian warning:
W: libam7xxx-dev: priority-extra-is-replaced-by-priority-optional
N:
N: Since Debian Policy version 4.0.1, the priority extra has been
N: deprecated.
N:
N: Please update debian/control and replace all instances of Priority:
N: extra with Priority: optional.
N:
N: Refer to Debian Policy Manual section 2.5 (Priorities) for details.
N:
N: Severity: minor, Certainty: certain
N:
N: Check: fields, Type: binary, udeb, source
N:
Source: libam7xxx
Section: libdevel
-Priority: extra
+Priority: optional
Maintainer: Antonio Ospite <ao2@ao2.it>
Build-Depends: debhelper (>= 9), dpkg-dev (>= 1.16.1~), cmake, pkg-config,
libusb-1.0-0-dev, libxcb1-dev,