ghc.mk: Use the same conditional install logic from unlit
authorMoritz Angermann <moritz.angermann@gmail.com>
Thu, 30 Nov 2017 00:21:45 +0000 (19:21 -0500)
committerBen Gamari <ben@smart-cactus.org>
Thu, 30 Nov 2017 00:21:46 +0000 (19:21 -0500)
commit738f3666c878ee9e79c3d5e819ef8b3460288edf
tree3c5064a26d2a1b09c87324ac640e028349673cc8
parent9483ad10064fbbb97ab525280623826b1ef63959
ghc.mk: Use the same conditional install logic from unlit

Summary:
This removes the make concurrency bug from the CrossCompilation
fix, and uses the same appraoch `utils/unlit` already uses. See:
https://git.haskell.org/ghc.git/commitdiff/ff84d052850b637b03bbb98cf05202e44886257d

Reviewers: bgamari, O25 HSC2HS, hvr

Differential Revision: https://phabricator.haskell.org/D4243
ghc.mk