The existence of CONFIG_SUBDIR hijacks INSTALL_CFGDIR to a subdirectory (by
default /etc/opt/<package>/$(CONFIG_SUBDIR)). Then std_install_rules apply,
and (the bent) INSTALL_CFGDIR is installed, but its parent directory, the
original $(INSTALL_CFGDIR), is not a prerequisite of install anylonger, and
has no rule anymore, hence log-install is never run for it. Instead it's
implicitly created by log-install -D $(INSTALL_CFGDIR).
This commit gives /etc/opt/<package> std-install rule and variables back as
CFGTOPDIR variants, and inserts it early into the install target's
prerequisite list.
Signed-off-by: Jan Lindemann <jan@janware.com>