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

gcc/testsuite/ChangeLog

+2018-12-05  David Malcolm  <dmalcolm@redhat.com>
+
+	* lib/gcc-dg.exp (process-message): Change verbosity level of
+	"verbose" from 2 to 3.
+	(dg-locus): Likewise.
+
 2018-12-05  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/63184

gcc/testsuite/lib/gcc-dg.exp

@@ -1165,7 +1165,7 @@ proc process-message { msgproc msgprefix dgargs } {
     set newentry [lreplace $newentry 2 2 $expmsg]
 
     set dg-messages [lreplace ${dg-messages} end end $newentry]
-    verbose "process-message:\n${dg-messages}" 2
+    verbose "process-message:\n${dg-messages}" 3
 }
 
 # Look for messages that don't have standard prefixes.
@@ -1199,7 +1199,7 @@ proc dg-locus { args } {
 
     set newentry [lreplace $newentry 2 2 $expmsg]
     set dg-messages [lreplace ${dg-messages} end end $newentry]
-    verbose "process-message:\n${dg-messages}" 2
+    verbose "process-message:\n${dg-messages}" 3
 }
 
 # Handle output from -fopt-info for MSG_OPTIMIZED_LOCATIONS: