Make define_blocks warning a note #901

Job	Run time
build (-DOPENMP=on, -DCMAKE_BUILD_TYPE=Release)	11m 30s
build (-DOPENMP=on, -DCMAKE_BUILD_TYPE=Debug)	3m 31s
build (-DOPENMP=on, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Release)	12m 32s
build (-DOPENMP=on, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Debug)	3m 46s
build (-DOPENMP=on, -DWITH_YAML=on, -DCMAKE_BUILD_TYPE=Release)	12m 32s
build (-DOPENMP=on, -DWITH_YAML=on, -DCMAKE_BUILD_TYPE=Debug)	3m 33s
build (-DOPENMP=on, -DWITH_YAML=on, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Release)	12m 53s
build (-DOPENMP=on, -DWITH_YAML=on, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Debug)	3m 58s
build (-DOPENMP=off, -DCMAKE_BUILD_TYPE=Release)	11m 26s
build (-DOPENMP=off, -DCMAKE_BUILD_TYPE=Debug)	3m 28s
build (-DOPENMP=off, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Release)	12m 43s
build (-DOPENMP=off, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Debug)	3m 55s
build (-DOPENMP=off, -DWITH_YAML=on, -DCMAKE_BUILD_TYPE=Release)	12m 13s
build (-DOPENMP=off, -DWITH_YAML=on, -DCMAKE_BUILD_TYPE=Debug)	3m 41s
build (-DOPENMP=off, -DWITH_YAML=on, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Release)	14m 29s
build (-DOPENMP=off, -DWITH_YAML=on, -DUSE_DEPRECATED_IO=on, -DCMAKE_BUILD_TYPE=Debug)	3m 54s
	2h 10m 4s

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