Lint for Min/Max If Statements

Clippy should be able to detect instances where an if statement is being used to calculate the min or max of two or more values and recommend using the cmp::min/max functions instead. These two examples were taken from real-world code directly translated from C into Rust.

Example 1:

Unnecessary

let mut x = if a < b { a } else { b };
if x > y { x = y; }

Recommended

let x = cmp::min(cmp::min(a ,b), y);

Example 2:

Unnecessary

let mut count = (sum + stride / 2) / stride;
if count < 1 { count = 1; }
if sum == 0 { count = 0; }

Recommended

let count = if sum == 0 { 0 } else { cmp::max((sum + stride / 2) / stride, 1) };

Start with the two Rust examples in the issue and review Clippy's existing lint infrastructure for comparable transformations. Done means detecting equivalent min/max patterns and recommending cmp::min or cmp::max while preserving the conditional behavior shown in both examples; no file or test path is specified.