.b4-config: configure b4 for Buildroot

`b4` is a commandline tool to make patch-based development easier[1]. It
is primarily used for Linux kernel development, but can be configured to
support any project that has a public-inbox endpoint. Buildroot has a
public-inbox mirror at "https://lore.kernel.org/buildroot/".

We configure some basic settings that tell `b4` where to send patches
and how to use get-developers.

[1] https://b4.docs.kernel.org/en/latest/

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit 322213e131)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

.b4-config

@@ -0,0 +1,7 @@
+# Configuration for the `b4` tool
+# See https://b4.docs.kernel.org/en/latest/config.html
+[b4]
+    send-series-to = buildroot@buildroot.org
+    send-auto-cc-cmd = "./utils/get-developers -e -"
+
+# vim: set filetype=gitconfig: