syn: Remove bpf target support in hash feature

[acheroncrypto]

Problem

anchor-syn is used for code parsing and generation, but we also have hash feature that has bpf target related code:

anchor/lang/syn/src/hash.rs

Lines 101 to 116 in 0a1d458

	// Call via a system call to perform the calculation
	#[cfg(target_arch = "bpf")]
	{
	extern "C" {
	fn sol_sha256(vals: *const u8, val_len: u64, hash_result: *mut u8) -> u64;
	}
	let mut hash_result = [0; HASH_BYTES];
	unsafe {
	sol_sha256(
	vals as *const _ as *const u8,
	vals.len() as u64,
	&mut hash_result as *mut _ as *mut u8,
	);
	}
	Hash::new_from_array(hash_result)
	}

This whole module was copied from solana_program::hash, which is likely why bpf related code wasn't removed. On-chain hashing should be done using solana_program::hash, which has the exact same functionality.

Also, bpf target arch has been deprecated as mentioned in #3062 (comment).

Summary of changes

Remove bpf target arch related code.

[vercel]

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