build-llvm: Bump to LLVM 20.1.1 #1611

Job	Run time
prepare	4s
macos	2h 54m 30s
linux	3h 8m 18s
msys2 (clang64)	1h 55m 0s
msys2 (mingw64)	2h 17m 33s
linux-asserts	0s
linux-test-cross-build-ffmpeg	0s
linux-cross-aarch64	3h 19m 58s
linux-cross-windows (armv7, ucrt)	3h 11m 43s
linux-cross-windows (aarch64, ucrt)	3h 12m 28s
linux-cross-windows (i686, ucrt)	3h 9m 14s
linux-cross-windows (x86_64, ucrt)	3h 12m 4s
test-toolchain (x86_64)	2m 12s
test-toolchain (i686)	2m 17s
test-openmp	0s
test-compiler-rt	0s
test-ffmpeg	0s
test-libcxx	0s
upload-nightly	0s
	1d 2h 25m 21s

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