base64: windows: ensure stdout is binary-clean #265

Job	Run time	Billable time
makefile-analysis	33s	0s
cmake-alpine-amd64-gcc	10s	0s
makefile-alpine-amd64-gcc	11s	0s
cmake-alpine-armv7-gcc	1m 5s	0s
makefile-alpine-armv7-gcc	59s	0s
cmake-alpine-armv7-clang	1m 29s	0s
makefile-alpine-armv7-clang	1m 21s	0s
cmake-ubuntu-20.04-x86_64	7s	0s
cmake-alpine-aarch64-gcc	1m 24s	0s
makefile-alpine-aarch64-gcc	1m 9s	0s
makefile-ubuntu-20.04-amd64-gcc	6s	0s
cmake-alpine-aarch64-clang	1m 47s	0s
cmake-ubuntu-20.04-i686	21s	0s
makefile-alpine-aarch64-clang	1m 28s	0s
makefile-ubuntu-20.04-amd64-gcc +openmp	4s	0s
cmake-alpine-s390x-gcc	1m 20s	0s
cmake-macos-11-x86_64	34s	0s
makefile-alpine-s390x-gcc	1m 7s	0s
makefile-ubuntu-20.04-amd64-clang	6s	0s
cmake-alpine-s390x-clang	1m 46s	0s
cmake-windows-2019-x86_64	1m 51s	0s
makefile-alpine-s390x-clang	1m 30s	0s
makefile-ubuntu-20.04-amd64-clang +openmp	13s	0s
cmake-alpine-ppc64le-gcc	1m 10s	0s
cmake-windows-2019-i686	3m 21s	0s
makefile-alpine-ppc64le-gcc	54s	0s
cmake-alpine-ppc64le-clang	1m 40s	0s
makefile-macos-11-amd64-clang	19s	0s
makefile-alpine-ppc64le-clang	1m 54s	0s
msys2-makefile-msys	1m 38s	0s
msys2-cmake-msys	1m 38s	0s
msys2-makefile-mingw32	1m 57s	0s
msys2-cmake-mingw32	1m 56s	0s
msys2-makefile-mingw64	1m 53s	0s
msys2-cmake-mingw64	2m 9s	0s
msys2-makefile-ucrt64	1m 55s	0s
msys2-cmake-ucrt64	2m 24s	0s
msys2-cmake-clang32	2m 31s	0s
msys2-cmake-clang64	2m 2s	0s
	50m 2s	0s

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