[FYI] Fix build breakage with --disable-tui

[FYI] Fix build breakage with --disable-tui

[Tom Tromey]

An earlier patch introduced a unit test for tui_copy_source_line.
However if the TUI is not built (as is apparently the case on some of
the buildbot builders), then this will fail to link.

This patch fixes the problem.  Tested by rebuilding with the TUI
disabled.

gdb/ChangeLog
2019-12-02  Tom Tromey  <tom@tromey.com>

	* unittests/tui-selftests.c (run_tests): Make conditional.
	(_initialize_tui_selftest): Make conditional.

Change-Id: I964811c7635be24cf6c53920e74e920914503674
---
 gdb/ChangeLog                 | 5 +++++
 gdb/unittests/tui-selftests.c | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/gdb/unittests/tui-selftests.c b/gdb/unittests/tui-selftests.c
index 3a5d34fe48c..95c12e3f5d2 100644
--- a/gdb/unittests/tui-selftests.c
+++ b/gdb/unittests/tui-selftests.c
@@ -21,6 +21,8 @@
 #include "gdbsupport/selftest.h"
 #include "tui/tui-winsource.h"
 
+#ifdef TUI
+
 namespace selftests {
 namespace tui {
 
@@ -41,8 +43,12 @@ run_tests ()
 } /* namespace tui*/
 } /* namespace selftests */
 
+#endif /* TUI */
+
 void
 _initialize_tui_selftest ()
 {
+#ifdef TUI
   selftests::register_test ("tui", selftests::tui::run_tests);
+#endif
 }
-- 
2.17.2