Add better support for armv7a cross compilation #2815

Job	Run time
cabal-doExactConfig	1m 11s
build-extra-hackages	1m 9s
cabal	1m 10s
check-materialization-concurrency	23s
check-path-support	1m 12s
closure-size	3s
docs	26s
haskell-nix-roots-do-not-require-IFDs	1m 8s
hix	1m 3s
hix-cabal	43s
hydra-ifdLevel-0-and-1	20m 20s
hydra-ifdLevel-2	4m 45s
hydra-ifdLevel-3	7m 12s
hydra-without-remote-builders-ghc8107	7s
hydra-without-remote-builders-ghc9101	7s
multi-target	16m 21s
maintainer-scripts	7s
nix-build	58m 0s
nix-tools	15s
plan-extra-hackages	5s
runghc	10m 25s
shellFor-hoogle	15m 35s
shellFor-multiple-package	15m 43s
shellFor-not-depends	24s
shellFor-single-package	10m 58s
tests-benchmarks	25s
unit-tests	17s
update-docs	14s
	2h 49m 48s

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