Add better support for armv7a cross compilation #2955

Job	Run time
runghc	58s
nix-build	17m 57s
unit-tests	31s
multi-target	3m 50s
cabal	1m 16s
shellFor-multiple-package	3m 41s
tests-benchmarks	21s
shellFor-single-package	2m 58s
cabal-doExactConfig	1m 23s
build-extra-hackages	14s
check-materialization-concurrency	20s
check-path-support	13s
closure-size	4s
docs	3m 55s
haskell-nix-roots-do-not-require-IFDs	59m 21s
hix	1h 5m 33s
hydra-ifdLevel-0-and-1	4m 57s
hydra-ifdLevel-2	8m 47s
hydra-ifdLevel-3	30m 10s
maintainer-scripts	7s
plan-extra-hackages	8s
shellFor-hoogle	14s
update-docs	4s
shellFor-not-depends	18s
hix-cabal	1m 46s
hydra-without-remote-builders-ghc9101	3m 1s
hydra-without-remote-builders-ghc966	3m 33s
nix-tools	15s
	3h 35m 55s

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