Experimental: Libretro: Pause FreeJ2ME when libretro pauses as well

Doesn't work very well yet, mostly because some JVM subsystems rely
on the system's time, and the MIDI Sequencer also has issues resuming.

Nonetheless, it's a start, just has to be refined quite a bit, and
already works on nearly all of the tested jars without any issues
other than midi playback.

src/libretro/freej2me_libretro.c

@@ -657,6 +657,19 @@ void retro_unload_game(void)
 	quit(0);
 }
 
+void pauseFreeJ2ME(bool pause) 
+{
+#ifdef __linux__
+	// Note: Despite being a "kill" function, it really just sends a signal to stop and continue the process here 
+	if(pause) { kill(javaProcess, SIGTSTP); }
+	else { kill(javaProcess, SIGCONT); }
+#elif _WIN32
+	// NOTE: Untested, tries to suspend/resume java app's main thread.
+	if(pause) { SuspendThread(javaProcess.hThread); }
+	else { ResumeThread(javaProcess.hThread); }
+#endif
+}
+
 void retro_run(void)
 {
 	int i = 0;
@@ -673,6 +686,8 @@ void retro_run(void)
 	// These are only used if useAnalogAsEntireKeypad is enabled.
 	bool num1pressed = false, num3pressed = false, num7pressed = false, num9pressed = false;
 
+	pauseFreeJ2ME(false);
+
 	if (Environ(RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE, &updated_vars) && updated_vars) { check_variables(false); }
 
 	if(isRunning(javaProcess))
@@ -1059,6 +1074,8 @@ void retro_run(void)
 	else { retro_deinit(); }
 	/* send frame to libretro irrespective of FreeJ2ME running (for error messages) */
 	Video(frame, frameWidth, frameHeight, sizeof(unsigned int) * frameWidth);
+
+	pauseFreeJ2ME(true);
 }
 
 unsigned retro_get_region(void)