Add TRACE_FUNC to trace the file, line, and name of the calling
function. File and function names don't have to be duplicated in a
TRACE statement with this (they tend to become inaccurate as functions
are renamed and the TRACE statement is forgotten).
Add DEBUG_STACK to dump the bash stack to debug output.
Configure bash with --enable-debugger. Bash doesn't actually include
the entire debugger, this is just some supporting variables for it.
Evidently, BASH_SOURCE[n] is only set within a function if this is
enabled. I couldn't find this indicated in any documentation, but it
happened in practice.
Compressed initrd size only increased by 2560 bytes for librem_mini_v2,
I think that is fine. This also gives us BASH_ARGC/BASH_ARGV which
might be useful for diagnostics.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>