Panic compiling a memory operation with fuel and nonstandard configuration

[alexcrichton]

This input module:

(module
  (func
    (local i32 i64)
    local.get 0
    i64.load8_s offset=2147483631
    local.set 1
  )
  (memory  1 1)
)

will fail to compile with:

$ cargo run compile testcase0.wat --fuel 0 --static-memory-maximum-size 538976288 
...
thread '<unnamed>' panicked at 'assertion failed: `(left == right)`
  left: `2`,
 right: `0`', crates/cranelift/src/func_environ.rs:388:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

cc @fitzgen as bisection shows that this was a regression from #5386

[fitzgen]

Thanks! Looking into it.