Use MaybeUninit in DecInt #4449

Job	Run time
Check --no-default-features (nightly)	57s
Check nightly-only targets (nightly)	24s
Check selected Tier 3 platforms (nightly)	4m 49s
Check (stable)	5m 43s
Check (nightly)	5m 47s
Rustfmt	4s
Check (1.63)	5m 49s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 8s
Test (ubuntu)	41s
Test rustix_use_experimental_asm (s390x-linux)	1m 26s
Test use-libc (ubuntu)	49s
Test (ubuntu-20.04)	46s
Test use-libc (i686-linux)	1m 23s
Test (i686-linux)	1m 0s
Test use-libc (aarch64-linux)	1m 3s
Test (aarch64-linux)	1m 11s
Test use-libc (powerpc64le-linux)	1m 33s
Test (powerpc64le-linux)	1m 18s
Test use-libc (riscv64-linux)	55s
Test (riscv64-linux)	1m 17s
Test use-libc (s390x-linux)	1m 11s
Test (s390x-linux)	1m 5s
Test use-libc (arm-linux)	1m 24s
Test (arm-linux)	1m 6s
Test (ubuntu-stable)	37s
Test (i686-linux-stable)	52s
Test (aarch64-linux-stable)	58s
Test (riscv64-linux-stable)	52s
Test (s390x-linux-stable)	52s
Test (powerpc64le-linux-stable)	1m 30s
Test (arm-linux-stable)	53s
Test (ubuntu-1.63)	2m 29s
Test (i686-linux-1.63)	2m 48s
Test (aarch64-linux-1.63)	2m 55s
Test (riscv64-linux-1.63)	2m 54s
Test (s390x-linux-1.63)	2m 55s
Test (powerpc64le-linux-1.63)	2m 54s
Test (arm-linux-1.63)	3m 7s
Test (macos-latest)	46s
Test (macos-13)	58s
Test (windows)	57s
Test (windows-2019)	56s
Test (musl)	49s
	1h 13m 51s

Provide feedback