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

qemu-trace2txt

@@ -1,14 +1,27 @@
-#!/usr/bin/env bash
-. "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/common"
-while getopts "${common_getopts_flags}" OPT; do
-  case "$OPT" in
-    ?)
-      common_getopts_case "$OPT"
-      ;;
-  esac
-done
-common_setup
-./qemu/scripts/simpletrace.py \
-  "${common_build_dir}/host-qemu-custom/trace-events-all" \
-  "${common_qemu_run_dir}/trace.bin" \
-> "${common_trace_txt_file}"
+#!/usr/bin/env python3
+
+import os
+import subprocess
+import sys
+
+import common
+
+def main():
+    cmd = [
+        os.path.join(common.qemu_src_dir, 'scripts/simpletrace.py'),
+        os.path.join(common.qemu_build_dir, 'trace-events-all'),
+        os.path.join(common.qemu_trace_file),
+    ]
+    return common.run_cmd(
+        cmd,
+        cmd_file=os.path.join(common.run_dir, 'qemu-trace2txt'),
+        out_file=common.qemu_trace_txt_file,
+        show_stdout=False,
+    )
+
+if __name__ == '__main__':
+    parser = common.get_argparse(argparse_args={
+        'description': 'Convert a QEMU `-trace exec_tb` to text form.'
+    })
+    args = common.setup(parser)
+    sys.exit(main())