[dotest] Remove -q (quiet) flag.

This patch removes the -q (quiet) flag and changing the default
behavior. Currently the flag serves two purposes that are somewhat
contradictory, as illustrated by the difference between the argument
name (quiet) and the configuration flag (parsable). On the one hand it
reduces output, but on the other hand it prints more output, like the
result of individual tests. My proposal is to guard the extra output
behind the verbose flag and always print the individual test results.

Differential revision: https://reviews.llvm.org/D66837

llvm-svn: 370226