Shellcheck: Building v0.4.5 results in compilation error

[ghost]

For bugs

• My shellcheck version 0.4.5

This is on Ubuntu 14.04

```# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"

Running `cabal install` results in a compile error

#### Here's a snippet or screenshot that shows the problem:

cabal install

Resolving dependencies...
Configuring ShellCheck-0.4.5...
Building ShellCheck-0.4.5...
Preprocessing library ShellCheck-0.4.5...

...(snip many lines of successful compiling)...

[17 of 18] Compiling ShellCheck.Analyzer ( ShellCheck/Analyzer.hs, dist/build/ShellCheck/Analyzer.o )

ShellCheck/Analyzer.hs:41:19:
Not in scope: mconcat' Perhaps you meantconcat' (imported from Data.List)
Failed to install ShellCheck-0.4.5
cabal: Error: some packages failed to install:
ShellCheck-0.4.5 failed during the building phase. The exception was:
ExitFailure 1
```

Note: I checked out tag v0.4.4 and the build finished OK. So appears to be only a problem in tag v0.4.5

[PeterDaveHello]

FYI, I have no problem on Debian 8.

[hcpl]

cabal install also fails to build v0.4.5 on Travis CI under Ubuntu 12.04. Switching to stack and using stack install solved the issue for me.

[arth1]

The mconcat error also occurs on Red Hat Enterprise Linux 6 and ScientificLinux 6, with ghc-7.6.3, all up to date as per cabal update.
Building 0.4.5 from the cabal repository works; building from the svn repository does not.

[koalaman]

mconcat is probably accidentally exported by some module on some versions. a40efff explicitly adds the right import.

Please reopen if this is still an issue.