travis: remove travis_wait, only test "expr"
travis: remove travis_wait, only test "expr"

Build is taking more than 50 minutes (the limit for travis).  This will
hopefully reduce its time.  The other test suites will only be tested by
Makefile.

I tried looking into expanding the matrix based on different "script:" commands
or a separate "env:" list.  I don't think it is possible.  In Haskell projects,
travis will only expand the matrix to different things in "ghc:" and "env:".

rudymatela/speculate