testsuite: turn down verbosity of "process-message"

testsuite: turn down verbosity of "process-message"

When debugging a failing test, I typically invoke DejaGnu at
verbosity level 2 (via RUNTESTFLAGS="-v -v dg.exp=something"),
so that DejaGnu prints the command line used to invoke the
compiler; specifically these two sites:
  target.exp "Invoking the compiler as "
  remote.exp "Executing on $hostname"
which are both verbosity level 2.

Unfortunately I run into an O(n^2) issue with logging from
process-message:

  verbose "process-message:\n${dg-messages}" 2

where, as each message each processed, it emits the state
of dg-messages, containing the new message and all messages so far,
leading to exponentially-increasing output at level 2 as more test
messages are added.

This patch papers over the problem by moving the
problematic message to verbosity level 3.

gcc/testsuite/ChangeLog:
	* lib/gcc-dg.exp (process-message): Change verbosity level of
	"verbose" from 2 to 3.
	(dg-locus): Likewise.

From-SVN: r266828