machine-overrides-extender.bbclass: Postpone until 'RecipeParsed' event
The 'ConfigParsed' event was too early and when we mangled the
MACHINEOVERRIDES using the extender, we ended overriding some values
when using together with multilib.
This fixes the multilib use-case and keep current ones working.
Change-Id: I6f1d952dfe2d04fa10229a86763af4ca6b1e601f Reported-by: Cristinel Panfir <cristinel.panfir@nxp.com> Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
