gdb/testsuite/tui: Always dump_screen when asked

The Term::dump_screen routine currently dumps the screen using calls
to 'verbose', this means it will only dump the screen when the
testsuite is running in verbose mode.

However, the Term::dump_screen is most often called when a test fails,
in this case I think it is useful to have the screen dumped even when
we're not in verbose mode.

This commit changes the calls to 'verbose' to be 'verbose -log' so we
always get the screen dump.

gdb/testsuite/ChangeLog:

	* lib/tuiterm.exp (Term::dump_screen): Always dump the screen when
	called.

Change-Id: I5f0a7f5ac2ece04d6fe6e9c5a28ea2a0dda38955

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2020-01-09  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* lib/tuiterm.exp (Term::dump_screen): Always dump the screen when
+	called.
+
 2020-01-09  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* gdb.base/skip.exp: Fix race condition in test.

gdb/testsuite/lib/tuiterm.exp

@@ -595,10 +595,10 @@ namespace eval Term {
     proc dump_screen {} {
 	variable _rows
 	variable _cols
-	verbose "Screen Dump ($_cols x $_rows):"
+	verbose -log "Screen Dump ($_cols x $_rows):"
 	for {set y 0} {$y < $_rows} {incr y} {
 	    set fmt [format %5d $y]
-	    verbose "$fmt [get_line $y]"
+	    verbose -log "$fmt [get_line $y]"
 	}
     }