Fix var-set-format MI result processing for LLDB

[iridinite]

Unlike GDB, LLDB-MI has a different result format for var-set-format. It wraps the new value in an array which only ever has one element. I'm not sure why that is the case, but it stops custom formats in Natvis from working.

Min repro:

struct Wrapper
{
	int mFoo;
};

int main(int argc, char* argv[])
{
	Wrapper w;
	w.mFoo = 123456789;

	__builtin_debugtrap();
}

Natvis:

<Type Name="Wrapper">
	<DisplayString>{mFoo,x}</DisplayString>
</Type>

Before

After