Add `ifreq`, `ifconf` and related constants to Android #5001

Job	Run time
Docker Linux Tier1 (i686-unknown-linux-gnu)	3m 16s
macOS (x86_64-apple-darwin)	2m 49s
Docker Linux Tier1 (x86_64-unknown-linux-gnu)	3m 33s
Windows (x86_64-pc-windows-gnu, 64, x86_64)	1m 55s
Style check	11s
Windows (x86_64-pc-windows-msvc)	3m 8s
Windows (i686-pc-windows-gnu, 32, i686)	2m 4s
Windows (i686-pc-windows-msvc)	1m 46s
	18m 42s

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