clippy: fix warnings from Rust 1.86

[cakebaker]

This PR fixes warnings from the manual_div_ceil and double_ended_iterator_last lints.

[codecov]

Codecov Report

Attention: Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.

Project coverage is 87.30%. Comparing base (013be1b) to head (5cb273e).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/find/matchers/printf.rs	0.00%	1 Missing ⚠️
src/xargs/mod.rs	85.71%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #522   +/-   ##
=======================================
  Coverage   87.30%   87.30%           
=======================================
  Files          31       31           
  Lines        6822     6824    +2     
  Branches      327      327           
=======================================
+ Hits         5956     5958    +2     
  Misses        631      631           
  Partials      235      235           

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[tavianator]

Might as well make the same fix right above:

findutils/src/find/matchers/printf.rs

Line 396 in 5235d78

let blocks = (meta()?.len() + STANDARD_BLOCK_SIZE - 1) / STANDARD_BLOCK_SIZE;

Side note: I think the code here is wrong, but that can be fixed in a different PR. It should be more like

let blocks = meta()?.blocks();
let len = blocks * STANDARD_BLOCK_SIZE;
let bs = if *large_blocks { 1024 } else { 512 };
blocks.div_ceil(len, bs)