travis-ci: don't be '--quiet' when running the tests

travis-ci: don't be '--quiet' when running the tests

All Travis CI build jobs run the test suite with 'make --quiet test'.

On one hand, being quiet doesn't save us from much clutter in the
output:

  $ make test |wc -l
  861
  $ make --quiet test |wc -l
  848

It only spares 13 lines, mostly the output of entering the 't/'
directory and the pre- and post-cleanup commands, which is negligible
compared to the ~700 lines printed while building Git and the ~850
lines of 'prove' output.

On the other hand, it's asking for trouble.  In our CI build scripts
we build Git and run the test suite in two separate 'make'
invocations.  In a prelimiary version of one of the later patches in
this series, to explicitly specify which compiler to use, I changed
them to basically run:

  make CC=$CC
  make --quiet test

naively thinking that it should Just Work...  but then that 'make
--quiet test' got all clever on me, noticed the changed build flags,
and then proceeded to rebuild everything with the default 'cc'.  And
because of that '--quiet' option, it did so, well, quietly, only
saying "* new build flags", and it was by mere luck that I happened to
notice that something is amiss.

Let's just drop that '--quiet' option when running the test suite in
all build scripts.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>