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

gem5-stat

@@ -1,25 +1,14 @@
-#!/usr/bin/env bash
-. "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/common"
-common_gem5=true
-while getopts "h${common_getopts_flags}" OPT; do
-  case "$OPT" in
-    h)
-      printf "\
-usage: $0 [-a arch] [stat=system.cpu.numCycles]
-Get the value for a gem5 stat from the stats.txt file.
-" 1>&2
-      exit
-      ;;
-    ?)
-      common_getopts_case "$OPT"
-      ;;
-  esac
-done
-shift "$(($OPTIND - 1))"
-if [ $# -gt 0 ]; then
-  stat="$1"
-else
-  stat=system.cpu[0-9]*.numCycles
-fi
-common_setup
-awk "/^$stat /{ print \$2 }" "${common_m5out_dir}/stats.txt"
+#!/usr/bin/env python3
+import common
+parser = common.get_argparse(
+    argparse_args={'description':'Get the value of a gem5 stat from the stats.txt file.'}
+)
+parser.add_argument(
+    'stat',
+    default=None,
+    help='Python regexp matching the full stat name of interest',
+    nargs='?',
+)
+args = common.setup(parser)
+stats = common.get_stats(args.stat)
+print('\n'.join(stats))