Address review: warn if system library was not found #71

Job	Run time
i686-pc-windows-msvc/msvc (Debug)	19m 30s
i686-pc-windows-msvc/msvc (Release)	8m 31s
x86_64-pc-windows-msvc/msvc (Debug)	18m 47s
x86_64-pc-windows-msvc/msvc (Release)	7m 47s
aarch64-pc-windows-msvc/msvc (Debug)	5m 9s
aarch64-pc-windows-msvc/msvc (Release)	5m 12s
x86_64-apple-darwin/clang (Debug)	11m 46s
x86_64-apple-darwin/clang (Release)	14m 40s
aarch64-apple-darwin/clang (Debug)	9m 1s
aarch64-apple-darwin/clang (Release)	15m 52s
x86_64-unknown-linux-gnu/gcc (Debug)	8m 17s
x86_64-unknown-linux-gnu/gcc (Release)	9m 20s
x86_64-unknown-linux-gnu/clang (Debug)	8m 5s
x86_64-unknown-linux-gnu/clang (Release)	8m 46s
aarch64-unknown-linux-gnu/gcc (Debug)	1h 15m 12s
aarch64-unknown-linux-gnu/gcc (Release)	57m 51s
aarch64-unknown-linux-gnu/clang (Debug)	1h 12m 54s
aarch64-unknown-linux-gnu/clang (Release)	1h 15m 16s
	7h 11m 56s

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