Add compiler to the build matrix in Travis CI
Add compiler to the build matrix in Travis CI

Sadly, the "compiler" setting does not seem to be supported for
languages that are not C/C++ or similar.

Signed-off-by: Krzysztof Wilczyński <5f1c0be89013f8fde969a8dcb2fa1d522e94ee00@linux.com>

kwilczynski/ruby-magic,kwilczynski/ruby-magic