Remove deprecated no-op function (1/2)

Glib::thread_init has been deprecated since 2.32,ib
is no longer necessary and no longer has any effect.

This fixes builds with modern glib[mm] versions, notably
with msys2 in Windows.

libs/ardour/test/testrunner.cc

@@ -19,10 +19,6 @@ static const char* localedir = LOCALEDIR;
 int
 main(int argc, char* argv[])
 {
-	if (!Glib::thread_supported()) {
-		Glib::thread_init();
-	}
-
 	const struct option longopts[] = {
 		{ "debug", 1, 0, 'D' },
 		{ 0, 0, 0, 0 }

libs/audiographer/tests/test_runner.cc

@@ -4,7 +4,6 @@
 
 int main()
 {
-	Glib::thread_init();
 	CppUnit::TextUi::TestRunner runner;
 	CppUnit::TestFactoryRegistry &registry = CppUnit::TestFactoryRegistry::getRegistry();
 	runner.addTest (registry.makeTest());

libs/pbd/pbd.cc

@@ -87,10 +87,6 @@ PBD::init ()
 	}
 #endif
 
-	if (!Glib::thread_supported()) {
-		Glib::thread_init();
-	}
-
 	Gio::init ();
 
 	PBD::ID::init ();

libs/pbd/test/rcu_test.cc

@@ -15,9 +15,6 @@ CPPUNIT_TEST_SUITE_REGISTRATION (RCUTest);
 void
 RCUTest::setUp ()
 {
-	if (!Glib::thread_supported ()) {
-		Glib::thread_init ();
-	}
 }
 
 static void*

libs/pbd/test/signals_test.cc

@@ -10,9 +10,6 @@ CPPUNIT_TEST_SUITE_REGISTRATION (SignalsTest);
 void
 SignalsTest::setUp ()
 {
-	if (!Glib::thread_supported ()) {
-		Glib::thread_init ();
-	}
 }
 
 class Emitter {

libs/temporal/test/testrunner.cc

@@ -17,10 +17,6 @@
 int
 main(int argc, char* argv[])
 {
-	if (!Glib::thread_supported()) {
-		Glib::thread_init();
-	}
-
 	const struct option longopts[] = {
 		{ "debug", 1, 0, 'D' },
 		{ 0, 0, 0, 0 }