Figure out how time distribution is computed on harness module or function module

[zjp-CN]

core::f64 module has time distribution, but there are no harness under it.
The time matrix is probably computed for a function module, instead of harness module.
However, it'd be weird to have zero harness on the right chart with verification time on the left.
Maybe it'd be good to compute time merely on harness module.

Harness Name: 
convert::num::verify::check_f16_to_int_unchecked::f64::i128::check_float_to_int_unchecked
Crate: core
Harness File: core/src/convert/num.rs
Harness Hash: 1797053298718753334516989592935679000737
Proof Kind: Contract
Total Properties: 48
Execution Time: 89ms

Verified Function: 
f64::<impl f64>::to_int_unchecked
Function File: core/src/num/f64.rs

[zjp-CN]

• cc Update charts on autoharnesses #138 (comment)
• cc Harness count is inaccurate #139

Now float modules have no harnesses, but the function count is mainfold.