Log Message:
pkgtools/pkg_comp: Correct usage of ${PKG_SYSCONFDIR}.

Package configuration files should be found in ${PKG_SYSCONFDIR},
which can be modified by a user-settable variable.  Look for the
default sandboxctl(8) configuration files in
${PKG_SYSCONFDIR.sandboxctl} if that variable is set, or else in
${PKG_SYSCONFBASE}/sandboxctl.

Fixes problem noted by Iain Hibbert on tech-pkg@.

Bump the PKGREVISION to 2 due to changes in the binary package if
PKG_SYSCONFDIR.pkg_comp is set to a non-default value.