Solang should not ask functions that contain address.call to be declared as view

[LucasSte]

Functions that modify the state, like the SPL-token mint_to, are not view functions, but the compiler warns that they can be declared as view.

Example:

	function mint_to(address mint, address account, address authority, uint64 amount) internal {
		bytes instr = new bytes(9);

		instr[0] = uint8(TokenInstruction.MintTo);
		instr.writeUint64LE(amount, 1);

		AccountMeta[3] metas = [
			AccountMeta({pubkey: mint, is_writable: true, is_signer: false}),
			AccountMeta({pubkey: account, is_writable: true, is_signer: false}),
			AccountMeta({pubkey: authority, is_writable: true, is_signer: true})
		];

		tokenProgramId.call{accounts: metas}(instr);
	}

Warning:

warning: function can be declared 'view'
   ┌─ /solang/solana-library/spl_token.sol:46:2
   │
46 │     function mint_to(address mint, address account, address authority, uint64 amount) internal {
   │