Rename to allow_tui_tests

This changes skip_tui_tests to invert the sense, and renames it to
allow_tui_tests.  It also rewrites this function to use the output of
"gdb --configuration", and it adds a note about the state of the TUI
to that output.

gdb/testsuite/gdb.base/options.exp

@@ -47,7 +47,7 @@ if { ![readline_is_used] } {
     return -1
 }
 
-set tui_supported_p [expr ![skip_tui_tests]]
+set tui_supported_p [allow_tui_tests]
 
 # Check the completion result, as returned by the "maintenance show
 # test-options-completion-result" command.  TEST is used as test name.

gdb/testsuite/gdb.python/tui-window-disabled.exp

@@ -22,6 +22,7 @@
 # though the tui should be disabled.
 
 load_lib gdb-python.exp
+require allow_tui_tests
 tuiterm_env
 
 standard_testfile
@@ -31,9 +32,6 @@ if {[build_executable "failed to prepare" ${testfile} ${srcfile}] == -1} {
 }
 
 clean_restart
-if {[skip_tui_tests]} {
-    return
-}
 
 # Copy the Python script to where the tests are being run.
 set remote_python_file [gdb_remote_download host \

gdb/testsuite/gdb.python/tui-window-names.exp

@@ -18,16 +18,12 @@
 
 load_lib gdb-python.exp
 
-require allow_python_tests
+require allow_python_tests allow_tui_tests
 
 tuiterm_env
 
 clean_restart
 
-if {[skip_tui_tests]} {
-    return
-}
-
 # Define a function we can use as a window constructor.  If this ever
 # gets called we'll throw an error, but that's OK, this test doesn't
 # actually try to create any windows.

gdb/testsuite/gdb.python/tui-window.exp

@@ -16,7 +16,7 @@
 # Test a TUI window implemented in Python.
 
 load_lib gdb-python.exp
-require allow_python_tests
+require allow_python_tests allow_tui_tests
 tuiterm_env
 
 # This test doesn't care about the inferior.
@@ -27,9 +27,6 @@ if {[build_executable "failed to prepare" ${testfile} ${srcfile}] == -1} {
 }
 
 clean_restart
-if {[skip_tui_tests]} {
-    return
-}
 
 Term::clean_restart 24 80 $testfile
 

gdb/testsuite/gdb.tui/completion.exp

@@ -13,10 +13,12 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+require allow_tui_tests
+
 gdb_exit
 gdb_start
 
-if {[skip_tui_tests] || [target_info exists gdb,nointerrupts]} {
+if {[target_info exists gdb,nointerrupts]} {
     return
 }
 

gdb/testsuite/gdb.tui/tui-disasm-long-lines.exp

@@ -33,7 +33,7 @@ if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "$binfile" \
 
 clean_restart "$binfile"
 
-if {[skip_tui_tests]} {
+if {![allow_tui_tests]} {
     # TUI support is disabled.  Check for error message.
     gdb_test "layout asm" "Undefined command: \"layout\".  Try \"help\"."
     return

gdb/testsuite/gdb.tui/tui-layout.exp

@@ -16,16 +16,14 @@
 # Minimal testcase that just checks that the various "layout $foo"
 # commands do not cause gdb to crash.
 
+require allow_tui_tests
+
 standard_testfile
 
 if {[prepare_for_testing "failed to prepare" ${testfile} ${srcfile}]} {
     return -1
 }
 
-if {[skip_tui_tests]} {
-    return
-}
-
 # Test one layout command.  EXECUTION indicates whether to activate
 # the layout with or without execution.
 

gdb/testsuite/gdb.tui/tui-nl-filtered-output.exp

@@ -30,13 +30,11 @@
 #
 #  (gdb)
 
+require allow_tui_tests
+
 gdb_exit
 gdb_start
 
-if {[skip_tui_tests]} {
-    return
-}
-
 # Enable the TUI.
 
 set test "tui enable"

gdb/testsuite/lib/completion-support.exp

@@ -555,7 +555,7 @@ proc test_gdb_completion_offers_commands {input_line} {
 
     # TUI adds additional commands to the possible completions, so we
     # need different patterns depending on whether or not it is enabled.
-    if { [skip_tui_tests] } {
+    if { ![allow_tui_tests] } {
 	test_gdb_complete_multiple $input_line "" "" {
 	    "!"
 	    "actions"

gdb/testsuite/lib/gdb.exp

@@ -2572,20 +2572,11 @@ gdb_caching_proc allow_dlmopen_tests {
     return $allow_dlmopen_tests
 }
 
-# Return 1 if we should skip tui related tests.
+# Return 1 if we should allow TUI-related tests.
 
-proc skip_tui_tests {} {
-    global gdb_prompt
-
-    gdb_test_multiple "help layout" "verify tui support" {
-	-re "Undefined command: \"layout\".*$gdb_prompt $" {
-	    return 1
-	}
-	-re "$gdb_prompt $" {
-	}
-    }
-
-    return 0
+gdb_caching_proc allow_tui_tests {
+    set output [remote_exec host $::GDB --configuration]
+    return [expr {[string first "--enable-tui" $output] != -1}]
 }
 
 # Test files shall make sure all the test result lines in gdb.sum are

gdb/testsuite/lib/tuiterm.exp

@@ -778,7 +778,7 @@ namespace eval Term {
     # Setup ready for starting the tui, but don't actually start it.
     # Returns 1 on success, 0 if TUI tests should be skipped.
     proc prepare_for_tui {} {
-	if {[skip_tui_tests]} {
+	if {![allow_tui_tests]} {
 	    return 0
 	}
 

gdb/top.c

@@ -1649,6 +1649,16 @@ This GDB was configured as follows:\n\
 "));
 #endif
 
+#ifdef TUI
+  gdb_printf (stream, _("\
+	     --enable-tui\n\
+"));
+#else
+  gdb_printf (stream, _("\
+	     --disable-tui\n\
+"));
+#endif
+
 #ifdef RELOC_SRCDIR
   gdb_printf (stream, _("\
 	     --with-relocated-sources=%s\n\