Experimental threading toolchain-only branch #1187

Job	Run time
Build only sysroot - exceptions	2m 6s
Build only sysroot - default	1m 51s
Build only sysroot - static	2m 7s
Build x86_64-macos	8m 21s
Build riscv64-linux	8m 15s
Build arm64-linux	8m 2s
Build arm64-macos	8m 15s
Build x86_64-linux	8m 15s
Build arm64-windows	8m 21s
Build x86_64-windows	8m 21s
Finalize wasi-sdk artifacts	1s
	1h 3m 55s

Provide feedback