Fix debugger build on Mac OS X 10.5/x86

Some more APIs were incorrectly checked for with __POWERPC__, even
though they have nothing to do with the architecture, but were only
introduced in Mac OS X 10.6.

librz/debug/p/native/xnu/xnu_debug.c

@@ -1154,8 +1154,10 @@ static void xnu_map_free(RzDebugMap *map) {
 }
 
 static RzList *xnu_dbg_modules(RzDebug *dbg) {
-#if __POWERPC__
+#if !defined(MAC_OS_X_VERSION_10_7)
 #warning TODO: xnu_dbg_modules not supported
+	// TASK_DYLD_INFO introduced in 10.6
+	// TASK_DYLD_ALL_IMAGE_INFO_* introduced in 10.7
 	return NULL;
 #else
 	rz_return_val_if_fail(dbg && dbg->plugin_data, NULL);

librz/debug/p/native/xnu/xnu_threads.c

@@ -220,7 +220,9 @@ RZ_IPI bool rz_xnu_thread_get_gpr(RzXnuDebug *ctx, xnu_thread_t *thread) {
 }
 
 static bool xnu_fill_info_thread(RzDebug *dbg, xnu_thread_t *thread) {
-#if __POWERPC__
+#if !defined(MAC_OS_X_VERSION_10_6)
+	// THREAD_IDENTIFIER_INFO introduced in 10.6
+	// TODO: use e.g. only basic info as a fallback here
 	thread->name = strdup("unknown");
 	return false;
 #else