systemcontract: multiply before divide

[txhsl]

No description provided.

[dusmart]

the values of (𝑎÷𝑏)÷𝑐 and 𝑎÷(𝑏×𝑐) are equal.

what multiply before divide principle state is that use (a*b)/c instead of (a/c)*b

https://math.stackexchange.com/questions/2557458/is-a-b-c-equal-to-a-bc-for-integer-division#:~:text=This%20corresponds%20to%20the%20integer,b%C3%97c)%20are%20equal.

By the way, the price for * and / are the same.

go-ethereum/core/vm/jump_table.go

Lines 267 to 272 in cada98a

	MUL: {
	execute: opMul,
	constantGas: GasFastStep,
	minStack: minStack(2, 1),
	maxStack: maxStack(2, 1),
	},

go-ethereum/core/vm/jump_table.go

Lines 279 to 284 in cada98a

	DIV: {
	execute: opDiv,
	constantGas: GasFastStep,
	minStack: minStack(2, 1),
	maxStack: maxStack(2, 1),
	},

I'm Ok if the auditing team insist this change. This won't bring side effect anyway.

[AnnaShaleva]

Well, I'm also OK with these changes. Precision loss is inevitable anyway.

[AnnaShaleva]

Should anyone else review this PR?