Update iostreams from develop #2781

Job	Run time
b2-windows (windows-2019)	31m 20s
cmake-install-posix (ubuntu-20.04)	4m 31s
b2-posix (ubuntu-20.04)	12m 41s
cmake-install-posix (ubuntu-22.04)	5m 58s
b2-windows (windows-2022)	30m 15s
cmake-install-windows (windows-2019)	9m 39s
b2-posix (ubuntu-22.04)	12m 33s
cmake-install-posix (ubuntu-24.04)	5m 7s
cmake-install-windows (windows-2022)	10m 45s
b2-posix (ubuntu-24.04)	14m 4s
cmake-install-posix (macos-13)	8m 10s
cmake-test-posix (ubuntu-latest)	41m 13s
b2-posix (macos-13)	39m 22s
cmake-install-posix (macos-14)	4m 51s
b2-posix (macos-14)	12m 44s
cmake-install-posix (macos-15)	4m 54s
cmake-test-posix-quick (ubuntu-20.04)	5m 16s
b2-posix (macos-15)	13m 39s
cmake-test-posix-quick (ubuntu-22.04)	2m 57s
cmake-test-windows-quick (windows-2019)	9m 14s
cmake-test-posix-quick (ubuntu-24.04)	2m 52s
cmake-test-windows-quick (windows-2022)	5m 58s
cmake-test-posix-quick (macos-13)	5m 4s
cmake-test-posix-quick (macos-14)	4m 36s
cmake-test-posix-quick (macos-15)	3m 55s
	5h 1m 38s

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