Add better support for armv7a cross compilation #2923

Job	Run time
nix-build	33s
runghc	8s
unit-tests	4s
cabal	9s
cabal-doExactConfig	10s
maintainer-scripts	7s
multi-target	33s
plan-extra-hackages	8s
shellFor-hoogle	10s
shellFor-multiple-package	11s
shellFor-not-depends	15s
shellFor-single-package	17s
tests-benchmarks	11s
build-extra-hackages	9s
check-materialization-concurrency	25s
check-path-support	6s
closure-size	4s
docs	22m 5s
haskell-nix-roots-do-not-require-IFDs	14s
hix	7m 50s
hydra-ifdLevel-0-and-1	6m 19s
hydra-ifdLevel-2	7m 3s
hydra-ifdLevel-3	30m 10s
update-docs	7s
hix-cabal	8s
hydra-without-remote-builders-ghc9101	41s
hydra-without-remote-builders-ghc966	1m 15s
nix-tools	35s
	1h 20m 7s

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