RFC: add a command line option to print out method invalidations to stderr or a file

[KristofferC]

This makes it work the same as --trace-compile.

❯ ./julia --trace-method-invalidations=stderr -e 'f() = 1; f(); f() = 2'
-- f()


❯ ./julia --trace-method-invalidations=invalidations.txt -e 'f() = 1; f(); f() = 2'
❯ cat invalidations.txt
-- f()

It is harder to toggle this in a running session now though so maybe this API isn't the best. Perhaps it is better to be able to scope a block of code to write the invalidations to a file.

cc @timholy, could potentially be used in timholy/SnoopCompile.jl#77.

Also, I don't know much about how things are structured in the code here so I just put stuff a bit randomly...

[timholy]

I wonder if it would be even better to say @snoopinvalid using SomePkg and have it return a data structure that facilitates analysis. That might suggest that we should instead focus on passing an IO object in and have it log the results there instead of JL_STDOUT.

[maleadt]

It is harder to toggle this in a running session now though so maybe this API isn't the best.

Maybe add an API like what we have for dump compiles:

julia/src/jitlayers.cpp

Lines 38 to 43 in b472f88

	JL_STREAM *dump_compiles_stream = NULL;
	extern "C" JL_DLLEXPORT
	void jl_dump_compiles(void *s)
	{
	dump_compiles_stream = (JL_STREAM*)s;
	}

[timholy]

xref #35768

[KristofferC]

Superseded.