PackageQueue: Use std::mutex/std::condition_variable instead of pthread types
PackageQueue: Use std::mutex/std::condition_variable instead of pthread types

This simplifies the code as we can make use of RAII.

Change-Id: Idbec11a1f8508c061f54e4394f20f37ddabb5025
Reviewed-by: Scott Parlane <85029adc3fa41ef14594a57826619713bfe95f25@alliedtelesis.co.nz>
Reviewed-by: Ridge Kennedy <c60c433c4c1ae237d133641099200771ff6f6f30@alliedtelesis.co.nz>
Signed-off-by: Matt Bennett <e3d8681cec70d3da741935b3385821001b249adc@alliedtelesis.co.nz>

alliedtelesis/buildsyspp,ATL-NZ/buildsyspp