boot/barebox-aux: exclude git downloads from hash check

When barebox, and thus barebox-aux, are downloaded from a git tree, then
barebox-aux download fails because a hash check is attempted on the
downloaded archive:

    Could not fetch special ref 'v2020.03.0'; assuming it is not special.
    ERROR: No hash found for barebox-aux-v2020.03.0.tar.gz

This is because we only exclude from the check the archive of the bare
barebox:

    BR_NO_CHECK_HASH_FOR += $(BAREBOX_SOURCE)

However, the default name of an archive is based on the package name,
which for barebox-aux is not 'barebox'.

Since barebox-aux really uses the exact same source as the bare barebox,
it should also share the archive name.

This has two direct consequences and advantages:

  - the hash check is completely avoided for the barebox-aux archive;

  - the barebox-aux archive is not downloaded as it is already
    downloaded for barebox.

Reported-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Tested-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 451ee6fa5454158b5d95cef0f404c0443dde868e)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

boot/barebox/barebox.mk

@@ -25,6 +25,10 @@ $(1)_SOURCE = $$(notdir $$($(1)_TARBALL))
 else ifeq ($$(BR2_TARGET_BAREBOX_CUSTOM_GIT),y)
 $(1)_SITE = $$(call qstrip,$$(BR2_TARGET_BAREBOX_CUSTOM_GIT_REPO_URL))
 $(1)_SITE_METHOD = git
+# Override the default value of _SOURCE to 'barebox-*' so that it is not
+# downloaded a second time for barebox-aux; also alows avoiding the hash
+# check:
+$(1)_SOURCE = barebox-$$($(1)_VERSION).tar.gz
 else
 # Handle stable official Barebox versions
 $(1)_SOURCE = barebox-$$($(1)_VERSION).tar.bz2