download/git: fix transform-name

When a package contains a relative symlink which first component is '..'
(thus pointing one directory higher), for example package 'meh' contains
this symlink:

    foo/bar -> ../buz

then it would be stored as 'meh-version./buz' because of the
transform-name pattern replacement.

Fix it to only match the leading './'.

Reported-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Reviewed-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Tested-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/download/git

@@ -111,7 +111,7 @@ LC_ALL=C sort <"${output}.list" >"${output}.list.sorted"
 
 # Create GNU-format tarballs, since that's the format of the tarballs on
 # sources.buildroot.org and used in the *.hash files
-tar cf - --transform="s/^\./${basename}/" \
+tar cf - --transform="s/^\.\//${basename}\//" \
 	--numeric-owner --owner=0 --group=0 --mtime="${date}" --format=gnu \
          -T "${output}.list.sorted" >"${output}.tar"
 gzip -6 -n <"${output}.tar" >"${output}"