buildroot

package/glibc: switch to downloading a tarball

Currently, we do a full git clone of the repository, which takes quite
some time, especially on slow networks.

This was done like that because the initial patch was using the official
repository as the source of the download, and that repository did not
offer remotely-generated tarballs.

But now we've switched to using a mirror on github, which does provide
such a tarball, which provides faster downloads.

Use that.

However, the tarball from github differs from the one we were generating
locally, because the paths inside are different. WE used to create a
archive with paths starting with glibc-glibc-2.26-73-g4b692dfb95[...],
while github does away with the git-describe prefix, and generates paths
that start with just glibc-4b692dffb95[...]. The content are exactly
identicall (checked with a diff), though.

Update the hash accordingly.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Waldemar Brodkorb <wbx@openadk.org>
Cc: Romain Naour <romain.naour@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>