Set PIC for C as well. #2022

Job	Run time
nix-build	5m 6s
unit-tests	16s
runghc	26s
cabal-doExactConfig	31s
build-extra-hackages	14s
cabal	22s
check-materialization-concurrency	25s
check-path-support	30s
closure-size	7s
docs	1m 13s
haskell-nix-roots-do-not-require-IFDs	8s
hix	1m 2s
hix-cabal	7m 33s
hydra-ifdLevel-0-and-1	44s
hydra-ifdLevel-2	15s
hydra-ifdLevel-3-and-ghc-8-10	16s
hydra-ifdLevel-3-and-ghc-9-2	9s
hydra-without-remote-builders	3m 4s
hydra-ifdLevel-3-and-not-ghc-8-10-or-9-2	23s
maintainer-scripts	11s
multi-target	16s
plan-extra-hackages	19s
nix-tools	22s
shellFor-hoogle	12s
shellFor-multiple-package	32s
shellFor-not-depends	43s
tests-benchmarks	25s
shellFor-single-package	42s
update-docs	11s
	26m 37s

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