CMake

add dnn sources to CMake when compiling on arm with RTCD #12

Job	Run time
Test build with CMake 3.16.0	5m 15s
CMake MINGW	42s
CMake/Android/So/ARMv8/Release	45s
CMake/Android/So/X86/Release	1m 9s
CMake/Android/So/X64/Release	54s
CMake/Windows/Dll/X86/Release	1m 58s
CMake/Windows/Dll/X64/Release	2m 13s
CMake/Windows/Dll/ARMv8/Release	1m 23s
CMake/Linux/So/X64/Release	34s
CMake/MacOSX/So/X64/Release	34s
CMake/MacOSX/Framework/X64/Release	1m 41s
CMake/iOS/Dll/arm64/Release	56s
CMake/iOS/Framework/arm64/Release	59s
CMake/Windows/Lib/X86/Release	2m 19s
CMake/Windows/Lib/X64/Release	2m 31s
CMake/Windows/Lib/armv8/Release	1m 29s
CMake/Linux/Lib/X64/Release	6m 29s
CMake/MacOSX/Lib/X64/Release	1m 23s
CMake/iOS/Lib/arm64/Release	1m 0s
CMake/Android/Lib/ARMv8/Release	53s
CMake/Android/Lib/X86/Release	1m 10s
CMake/Android/Lib/X64/Release	1m 30s
CMake/CustomModes/Linux/Lib/X64/Release	1m 24s
CMake/AssertionsFuzz/Windows/Lib/X64/Release	2m 55s
CMake/AssertionsFuzz/Linux/Lib/X64/Release	1m 16s
CMake/AssertionsFuzz/MacOSX/Lib/X64/Release	1m 38s
	45m 0s

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