Packages such as Perl, Lua, shell scripts don't generate binary files.
Add PKGARCH:=all to them.

Signed-off-by: Deng Qingfang <dengqf6@mail2.sysu.edu.cn>

Minor adjustments for consistency between packages.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

Avoid using 'hg' (Mercurial) to download sources.

'hg' is not an official prerequisite and it is not installed
in all buildslaves in Openwrt and LEDE buildbots, which
leads to frequent build failures.

Download the .tar.gz source archive instead.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>

Signed-off-by: Lars Gierth <larsg@systemli.org>