Enable multithreading.

Mac/mwerks/mwerks_plugin_config.h

@@ -4,6 +4,7 @@
 
 #define USE_GUSI1		/* Stdio implemented with GUSI */
 /* #define USE_GUSI2		/* Stdio implemented with GUSI */
+#define WITH_THREAD		/* Use thread support (needs GUSI 2, not GUSI 1) */
 #define USE_MSL			/* Use MSL libraries */
 #ifdef USE_MSL
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */

Mac/mwerks/mwerks_shared_config.h

@@ -8,6 +8,7 @@
 
 /* #define USE_GUSI1		/* Stdio implemented with GUSI */
 #define USE_GUSI2		/* Stdio implemented with GUSI */
+#define WITH_THREAD		/* Use thread support (needs GUSI 2, not GUSI 1) */
 #define USE_MSL			/* Use Mw Standard Library (as opposed to Plaugher C libraries) */
 #define USE_CORE_TOOLBOX	/* Include core toolbox modules (Dlg,Ctl,Menu,Win,Res,Qd) */
 /* #define USE_TOOLBOX		/* Include all toolbox modules in core Python */

Mac/mwerks/mwerks_tkplugin_config.h

@@ -4,5 +4,6 @@
 
 #define USE_GUSI1		/* Stdio implemented with GUSI */
 /* #define USE_GUSI2		/* Stdio implemented with GUSI */
+#define WITH_THREAD		/* Use thread support (needs GUSI 2, not GUSI 1) */
 #define USE_TK			/* Include _tkinter module in core Python */
 #define MAC_TCL			/* This *must* be on if USE_TK is on */