Add a newline at the end of test files #16617

Job	Run time
Arch Linux	19m 51s
CUDA (on Arch)	7m 34s
Fedora	19m 54s
Gentoo	21m 15s
Arch / PyPy	19m 44s
OpenSUSE	16m 46s
Ubuntu Bionic	15m 12s
Ubuntu Rolling (gcc, g++)	20m 2s
Ubuntu Rolling (--unity=on -Ddefault_library=static, --no-unittests, gcc, g++)	13m 58s
Ubuntu Rolling (-Ddefault_library=both, --no-unittests, gcc, g++)	13m 54s
Ubuntu Rolling (clang, clang++)	22m 55s
Ubuntu Rolling (--unity=on, --no-unittests, clang, clang++)	15m 26s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, 0, gcc, g++)	13m 30s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, --unity=on, gcc, g++)	13m 41s
	3h 53m 42s

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