Build all dkms modules near the end of the image build.

Work around ordering issues that cause dkms modules to not always
be built for all installed kernels, add a post-install.d script to
the base element that will force the issue.
(Note that any module/kernel pairs with a pre-existing valid
module will not be rebuilt, so this should not impact performance
unnecessarily)

Change-Id: Iccea14c6318014cc7e1fec77e71c14a224f7b76e

elements/base/post-install.d/99-dkms

@@ -0,0 +1,19 @@
+#!/bin/sh
+# Trigger a run of dkms for all the modules installed
+# to ensure we have valid modules build for all.
+
+modules=$(dkms status | tr ',:' ' ' | awk '{ print $1 "/" $2 }')
+kernels=$(ls /usr/src/linux-headers-*-*-* -d | sed -e 's|/usr/src/linux-headers-||')
+__ARCH=$ARCH
+unset ARCH
+
+for module in $modules ; do
+  for kernel in $kernels ; do
+    dkms build $module -k $kernel
+    dkms install $module -k $kernel
+  done
+done
+
+ARCH=$__ARCH
+
+dkms status