Add better support for armv7a cross compilation #2664

Job	Run time
build-extra-hackages	22s
cabal	28s
cabal-doExactConfig	14s
check-materialization-concurrency	24s
check-path-support	13s
closure-size	8s
docs	56s
haskell-nix-roots-do-not-require-IFDs	31s
hix	49s
hydra-ifdLevel-0-and-1	6m 29s
hix-cabal	17s
hydra-ifdLevel-2	18m 52s
hydra-without-remote-builders-ghc8107	8s
hydra-ifdLevel-3	30m 10s
hydra-without-remote-builders-ghc9101	7s
maintainer-scripts	12s
multi-target	31s
nix-build	30s
nix-tools	9s
plan-extra-hackages	5s
runghc	7s
shellFor-hoogle	8s
shellFor-multiple-package	11s
shellFor-not-depends	11s
shellFor-single-package	14s
tests-benchmarks	7s
unit-tests	4s
update-docs	4s
	1h 2m 41s

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