crosscompiling fails wihout -j1 flag

for example

```
cabal --with-gcc=arm-linux-gnueabi-gcc-5 --with-ghc=arm-unknown-linux-gnueabi-ghc \
--with-ghc-pkg=arm-unknown-linux-gnueabi-ghc-pkg --with-ld=arm-linux-gnueabi-ld \
--with-strip=arm-linux-gnueabi-strip --reinstall -v install pipes
```

outputs https://gist.github.com/ra1u/d20112e9819bd9680a59#file-cabal-fail

but adding flag `-j1` works fine

cabal version is 1.22.1.1

Start by reproducing the cross-compilation command shown in the issue with Cabal 1.22.1.1 and compare its output with the same command using -j1. Read the linked failure gist to identify the parallel-build failure; done means the cross-compilation install succeeds without requiring -j1.

Written by the indexing model from the issue text.