test running the gdalinfo executable

[visr]

This does not fix #95, but tests whether it is fixed, because locally it works fine for me now, so the issue was probably fixed elsewhere.

[visr]

Hmm I see Windows CI is not happy: https://travis-ci.org/github/JuliaGeo/GDAL.jl/jobs/735439773#L172-L194. But there is no segfault at least.

OSX interestingly only fails on Julia 1.3, complaining about an older libcurl version: https://travis-ci.org/github/JuliaGeo/GDAL.jl/jobs/735439770#L213-L221

dyld: Library not loaded: @rpath/libcurl.4.dylib
  Referenced from: /Users/travis/.julia/artifacts/7b7b3b7cd82869eaa06aa1ac70bfc542bdbfa184/bin/gdalinfo
  Reason: Incompatible library version: gdalinfo requires version 11.0.0 or later, but libcurl.4.dylib provides version 10.0.0

cc @niclasmattsson

[visr]

Great, this actually works now with the newer builds.