gem5: update to 7bfb7f3a43f382eb49853f47b140bfd6caad0fb8

The update is required to include 3c3ca64b5f0dd9eef7b1ce1c65cc6e8e9147dd38
otherwise baremetal does not on VExpress.

baremetal: create a baremetal setup with crosstool-ng

buildroot: improve directory location: move out/dl inside
out/buildroot/download, and add a new out/buildroot/build level

tagline: generalize, deliver more value than howto, since now howtos
are starting to multiply

rename all top scripts to separate words with hyphen more consistently,
e.g. run-gdb instead of rungdb

getvar: list all variables

gem5: make m5out section to focus all releated information at

Prevent m5term Text file busy when rebuilding gem5 while it is running.

qemu-monitor

@@ -0,0 +1,24 @@
+#!/usr/bin/env expect
+# Ee have to use expect since QEMU 2.12: just piping commands
+# into telnet stopped working at that version.
+spawn telnet localhost 45454
+set prompt "\n(qemu) "
+expect $prompt
+if {$argc > 0} {
+  send "[concat [join $argv " "]]\r"
+  expect $prompt
+} else {
+  interact
+}
+
+# In order to treat input from stdin, we would need to differentiate between input from pipe vs terminal.
+# For bash we can do it as:
+# https://stackoverflow.com/questions/911168/how-to-detect-if-my-shell-script-is-running-through-a-pipe
+# but no one knows for Tcl:
+# https://stackoverflow.com/questions/43660612/how-to-check-if-stdin-stdout-are-connected-to-a-terminal-in-tcl
+# One option would also be to have a bash wrapper that calls this tcl script.
+# Related: https://stackoverflow.com/questions/10237872/expect-redirect-stdin
+#while {[gets stdin line] > 0} {
+  #expect $prompt
+  #send "$line\r"
+#}