pkg-infra: move the bzr download helper to a script

Maintaining the download helpers in the Makefile has proved to be a bit
complex, so move it to a shell script.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/download/bzr

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# We want to catch any command failure, and exit immediately
+set -e
+
+# Download helper for bzr
+# Call it with:
+#   $1: bzr repo
+#   $2: bzr revision
+#   $3: output file
+# And this environment:
+#   BZR       : the bzr command to call
+#   BR2_DL_DIR: path to Buildroot's download dir
+
+repo="${1}"
+rev="${2}"
+output="${3}"
+
+${BZR} export "${output}" "${repo}" -r "${rev}"