Readline multiline completer #1455

Job	Run time
Build slim tarball	1m 21s
x86_64-linux: with shared libraries	2h 28m 7s
aarch64-linux: with shared libraries	2h 10m 17s
x86_64-darwin: with shared libraries	2h 44m 6s
aarch64-darwin: with shared libraries	1h 49m 11s
	9h 13m 2s

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