New pot_extrator method to i18n module #17000

Job	Run time
Arch Linux	9m 43s
CUDA (on Arch)	7m 50s
Fedora	9m 42s
Gentoo	9m 42s
OpenSUSE	9m 44s
Ubuntu Bionic	9m 41s
Arch / PyPy	9m 42s
Ubuntu Rolling (gcc, g++)	7m 48s
Ubuntu Rolling (--unity=on -Ddefault_library=static, --no-unittests, gcc, g++)	9m 42s
Ubuntu Rolling (-Ddefault_library=both, --no-unittests, gcc, g++)	9m 42s
Ubuntu Rolling (clang, clang++)	8m 58s
Ubuntu Rolling (--unity=on, --no-unittests, clang, clang++)	9m 22s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, 0, gcc, g++)	9m 42s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, --unity=on, gcc, g++)	9m 43s
	2h 11m 1s

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