[aot] mono_aot_split_options handles \ incorrectly

[lambdageek]

The idea is that you can pass an option like --aot=foo=bar,baz="abc\"def\",xyz=012 and the AOT compiler will see options foo=bar, baz=abc"def and zyx=012.

But this line that is supposed to handle the character following a \ is wrong

runtime/src/mono/mono/mini/aot-compiler.c

Lines 8749 to 8750 in 68b90ac

	if (state == MONO_AOT_OPTION_STATE_ESCAPE)
	goto next;

it never resets the state back to MONO_AOT_OPTION_STATE_STRING, so everything after the \ until the end of the options is treated as a single long option: foo=bar, baz=abc\"def",xyz=012

Also the \ is itself never removed from the option - instead of bar=abc"def we get bar=abc\"def. (And this is a hard problem because we woudl need to copy or modify the string, which we don't otherwise do)

[lambdageek]

Not a regression, this seems to go back all the way to ~2015