VGM export: fix it under low-latency mode

src/engine/engine.h

@@ -271,7 +271,7 @@ class DivEngine {
   void nextRow();
   void performVGMWrite(SafeWriter* w, DivSystem sys, DivRegWrite& write, int streamOff, double* loopTimer, double* loopFreq, int* loopSample, bool isSecond);
   // returns true if end of song.
-  bool nextTick(bool noAccum=false);
+  bool nextTick(bool noAccum=false, bool inhibitLowLat=false);
   bool perSystemEffect(int ch, unsigned char effect, unsigned char effectVal);
   bool perSystemPostEffect(int ch, unsigned char effect, unsigned char effectVal);
   void recalcChans();

src/engine/playback.cpp

@@ -1472,11 +1472,11 @@ void DivEngine::nextRow() {
   firstTick=true;
 }
 
-bool DivEngine::nextTick(bool noAccum) {
+bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
   bool ret=false;
   if (divider<10) divider=10;
 
-  if (lowLatency && !skipping) {
+  if (lowLatency && !skipping && !inhibitLowLat) {
     tickMult=1000/divider;
     if (tickMult<1) tickMult=1;
   } else {

src/engine/vgmOps.cpp

@@ -1384,7 +1384,7 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version) {
         writeLoop=true;
       }
     }
-    if (nextTick() || !playing) {
+    if (nextTick(false,true) || !playing) {
       done=true;
       if (!loop) {
         for (int i=0; i<song.systemLen; i++) {