[gdb/testsuite] Two fixes in gdb.python/tui-window-disabled.exp

I ran test-case gdb.python/tui-window-disabled.exp on a configuration without
python support, and ran into:
...
PASS: $exp: cleanup_properly=True: initial restart: set pagination off
UNSUPPORTED: $exp: cleanup_properly=True: couldn't restart GDB
PASS: $exp: cleanup_properly=False: initial restart: set pagination off
UNSUPPORTED: $exp: cleanup_properly=False: couldn't restart GDB
...

After looking into the test-case, I realized that this is a consequence of
!allow_python_tests.

Handle this instead by requiring allow_python_tests, such that we get the usual
and more clear:
...
UNSUPPORTED: $exp: require failed: allow_python_tests
...

Also fix a return without value in clean_restart_and_setup, which if triggered
would cause:
...
ERROR: expected boolean value but got ""
...

Tested on x86_64-linux.

1 files changed, 2 insertions, 5 deletions

diff --git a/gdb/testsuite/gdb.python/tui-window-disabled.exp b/gdb/testsuite/gdb.python/tui-window-disabled.exp
index fc69b2b..1d10437 100644
--- a/gdb/testsuite/gdb.python/tui-window-disabled.exp
+++ b/gdb/testsuite/gdb.python/tui-window-disabled.exp
@@ -22,7 +22,7 @@
 # though the tui should be disabled.
 
 load_lib gdb-python.exp
-require allow_tui_tests
+require allow_tui_tests allow_python_tests
 tuiterm_env
 
 standard_testfile
@@ -49,9 +49,6 @@ proc clean_restart_and_setup { prefix } {
 
 	Term::clean_restart 24 80 $testfile
 
-	# Skip all tests if Python scripting is not enabled.
-	if { ![allow_python_tests] } { return 0 }
-
 	# Now source the python script.
 	gdb_test_no_output "source ${remote_python_file}" \
 	    "source ${testfile}.py"
@@ -64,7 +61,7 @@ proc clean_restart_and_setup { prefix } {
 
 	if {![runto_main]} {
 	    perror "test suppressed"
-	    return
+	    return 0
 	}
     }