Try to fix Travis CI MinGW builds

Listing i686-w64-mingw32-gcc as a compiler stopped working.
Travis tries to print version before installing it.

$ i686-w64-mingw32-gcc --version

/home/travis/build.sh: line 201: i686-w64-mingw32-gcc: command not found

The command "i686-w64-mingw32-gcc --version" failed and exited with 127 during setup.