cmake: cleanup unused warnings #3547

Job	Run time
linux-compiler-compatible (clang, Debug, libc++)	11m 56s
linux-compiler-compatible (clang, Release, libc++)	9m 47s
mac-compiler-compatible (macos-14, Debug)	12m 49s
mingw64-compiler-compatible-crosscompiling (i686, Debug)	16m 22s
mac-compiler-compatible (macos-14, Release)	10m 24s
win-compiler-compatible-2022 (x86, dynamic, Debug)	34m 14s
mingw64-compiler-compatible-crosscompiling (i686, Release)	14m 18s
win-compiler-compatible-2022 (x86, dynamic, Release)	29m 38s
mingw64-compiler-compatible-crosscompiling (x86_64, Debug)	15m 48s
mingw64-compiler-compatible-crosscompiling (x86_64, Release)	14m 52s
	2h 50m 8s

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