Infer dtor attributes etc. before checks for (deprecated) DeleteExp

[kinke]

When a function hasn't had its attributes inferred yet, but is checked for being pure/safe/..., it is for some reason set as impure/non-safe, and a later semantic analysis doesn't infer them anymore...

E.g.:

dmd/src/dmd/func.d

Lines 1337 to 1338 in b6526df

	if (flags & FUNCFLAG.purityInprocess)
	setImpure();

dmd/src/dmd/func.d

Lines 1376 to 1381 in b6526df

	if (flags & FUNCFLAG.purityInprocess)
	{
	flags &= ~FUNCFLAG.purityInprocess;
	if (fes)
	fes.func.setImpure();
	}

[dlang-bot]

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[12345swordy]

Should the dtor attributes be infer by default?