block-padding: implement ISO 10126 #297

Job	Run time
build (1.60.0, thumbv7em-none-eabi)	2m 4s
build (1.60.0, wasm32-unknown-unknown)	2m 32s
build (stable, thumbv7em-none-eabi)	13s
build (stable, wasm32-unknown-unknown)	13s
cross (aarch64-unknown-linux-gnu, 1.60.0)	2m 24s
cross (aarch64-unknown-linux-gnu, stable)	45s
cross (powerpc-unknown-linux-gnu, 1.60.0)	2m 25s
cross (powerpc-unknown-linux-gnu, stable)	41s
test (i686-unknown-linux-gnu, ubuntu-latest, 1.60.0, sudo apt update && sudo apt install gcc-mult...	2m 44s
test (x86_64-unknown-linux-gnu, ubuntu-latest, 1.60.0)	2m 17s
test (x86_64-pc-windows-msvc, windows-latest, 1.60.0)	2m 25s
test (x86_64-apple-darwin, macos-latest, 1.60.0)	3m 20s
minimal-versions / minimal-versions	25s
	22m 28s

Provide feedback