Use MaybeUninit in DecInt #4417

Job	Run time
Check selected Tier 3 platforms (nightly)	4m 48s
Check nightly-only targets (nightly)	24s
Check --no-default-features (nightly)	53s
Check (stable)	6m 18s
Rustfmt	11s
Check (nightly)	6m 24s
Check (1.63)	10m 45s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 2s
Test (ubuntu)	45s
Test use-libc (ubuntu)	45s
Test (ubuntu-20.04)	45s
Test use-libc (i686-linux)	58s
Test (i686-linux)	1m 0s
Test rustix_use_experimental_asm (s390x-linux)	1m 8s
Test (aarch64-linux)	1m 0s
Test use-libc (aarch64-linux)	1m 3s
Test (powerpc64le-linux)	1m 21s
Test use-libc (powerpc64le-linux)	1m 15s
Test (riscv64-linux)	1m 6s
Test use-libc (riscv64-linux)	1m 15s
Test (s390x-linux)	1m 2s
Test use-libc (s390x-linux)	1m 5s
Test (arm-linux)	1m 5s
Test use-libc (arm-linux)	1m 9s
Test (ubuntu-stable)	44s
Test (i686-linux-stable)	1m 7s
Test (aarch64-linux-stable)	1m 9s
Test (riscv64-linux-stable)	1m 17s
Test (s390x-linux-stable)	1m 6s
Test (powerpc64le-linux-stable)	1m 6s
Test (arm-linux-stable)	1m 9s
Test (ubuntu-1.63)	2m 12s
Test (i686-linux-1.63)	2m 36s
Test (aarch64-linux-1.63)	2m 25s
Test (riscv64-linux-1.63)	2m 34s
Test (s390x-linux-1.63)	2m 35s
Test (powerpc64le-linux-1.63)	2m 35s
Test (arm-linux-1.63)	2m 33s
Test (macos-latest)	37s
Test (macos-12)	1m 2s
Test (windows)	44s
Test (windows-2019)	1m 26s
Test (musl)	48s
	1h 17m 12s

Provide feedback