Fix build-bpf dependency related errors

[jacksondoherty]

error: target is not supported, for more information see: https://docs.rs/getrandom/#unsupported-targets
error[E0433]: failed to resolve: use of undeclared crate or module `imp`

fix found here: https://docs.solana.com/developing/on-chain-programs/developing-rust

error[E0599]: no method named `lock` found for struct `Stderr` in the current scope

fix found by using version settings of Solana Lab's hello world: https://github.com/solana-labs/example-helloworld