all: Allow multiple config files

This is somewhat an intrusive change, but necessary if we want
to upstream the kdump tooling while allowing great extent of
customizations on SteamOS.

With this change, we have now a kdump.d folder on /usr/share,
that holds configuration files in the same way sysctl.d does.
In other words, we can easily override default settings by
just having more configuration files, which are sourced
following natural name sorting, i.e., we have now the concept
of config file precedence in kdump.

Our default config file is called 00-default, so we eventually
might have a 01-steamos e.g., with Deck's custom settings.
This is planned to other package though.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

kdump-collect.sh

@@ -13,7 +13,13 @@
 #  output for the user.
 #
 
-. /usr/lib/kdump/kdump.conf
+#  We have a more controlled situation with regards the config
+#  files here, since we manually added them in the initrd and
+#  the validation also happened there, during such addition,
+#  hence not requiring checking here.
+for cfg in "/usr/lib/kdump/conf/"/*; do
+	. "$cfg"
+done
 
 VMCORE="/proc/vmcore"
 KDUMP_TIMESTAMP=$(date -u +"%Y%m%d%H%M")