Use assumenosideeffects in local-dce
Use assumenosideeffects in local-dce

Summary:
Thanks to the proguard parser work, we can now just check if a method
has been marked pure by the PG config.

Reviewed By: dariorussi, int3

Differential Revision: D3989072

fbshipit-source-id: ba4a50925959bd5101267da7f7be27a9580a4814

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