core/pkg-infra: set no-check-hash only for main download

core/pkg-infra: set no-check-hash only for main download

Currently, when the main download if from an SCM, we exclude all
downloads from being hash-checked, on the assumption that we don't
have hashes for downloads from an SCM.

However, the exclusion is computed on the DOWNLOAD macro, which is
called for each download of a package, thus effectively disabling
hash checks for extra downloads, even though those are only ever
download with wget.

What we really wanted to do, in fact, was to exclude just the main
download.

We fix that by appending the main source file to the global list of
excluded files, from within the generic-package infra itself.

Reported-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Tested-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>