lkmc v2-rc

Unsquashed version at v2-rc-unsquashed, but that cannot be merged as it
breaks bisects at several points. All bugs will not bisect to this
humongous change.

It all started with a conversion of the Bash scripts to Python, mainly
because I couldn't stand not being able to properly use --options for
run which has a million options.

Then since that required a full testing, I decided to do all the
refactorings that I had in mind at once, and so I did and it became
v2-rc.

This is the largest patch I have ever done! OMG a few weeks of extra time.
I'm never writing a Bash script for anything that starts getting big again.

Some of the features are:

* separate build-qemu and build-gem5 commands
* common: convert scripts to python. Add --option for everything
* rename build to build-buildroot now that we are splitting all the build
  commands, Linux kernel to follow
* move all git submodules to submodules/ and all buildroot packages to
  packages/
* refactor the out/ structure. Keep projects on toplevel, because guest
  projects separate archs and host ones don't, making a toplevel arch wrong
* do-release: rename to just release
  https://stackoverflow.com/questions/16174992/cant-get-argparse-to-read-quoted-string-with-dashes-in-it
* run: add --terminal and explain gem5 pdb
* just track the lvimrc
* store CLI kernel config fragment inside buildlroot to avoid conflicts
* gem5: document m5 initparam
* readme: make a bunch of things awesomer
* readme: fix broken refs
* parsec-benchmark: update to 75d55ac446a43c47efb1044844a108c6c330184c
  Could not fetch otherwise.
* gem5: M5_OVERRIDE_PY_SOURCE

packages/kernel_modules/make-host.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# We can almost do everything from the Makefile itself by using default values for
+#
+#    LINUX_DIR ?= "/lib/modules/$(uname -r)/build"
+#    BR2_EXTERNAL_KERNEL_MODULES_PATH="$(pwd)"
+#
+# The problem with that is that if you define those variables in your environment,
+# the build breaks, so this is more portable.
+#
+# Trying to add `-i` to overcome incompatible modules will fail,
+# because any build failure prevents the generation of all `.mod.c` files.
+
+j="$(($(nproc) - 2))"
+while getopts j: OPT; do
+  case "$OPT" in
+    'j')
+      j="$OPTARG"
+    ;;
+  esac
+done
+shift $(($OPTIND - 1))
+make -j "$j" KERNEL_MODULES_PATH="$(pwd)" LINUX_DIR="/lib/modules/$(uname -r)/build" "$@"
+make -C user/ -j "$j" "$@"