iidx: delay logic for iidx tt (#669)

## Link to GitHub Issue or related Pull Request, if one exists
Re-implements fix for #181 as it was removed by #668

## Description of change
Add two options to add artificial delay to turntable input. These
operate directly on the input logic (`get_tt`) which is called by I/O
emulation code.

Functionally, it's **identical** to the `Delay (experimental)` option we
had in the analog tab, just moved to Options tab.

## Testing
64 bit tdj: ok
64 bit ldj bi2a: ok
32 bit ldj ezusb: ok

Worth noting that TDJ bi2x_hook polls at 120Hz, bi2a at ~500Hz, and
ezusb at ~170Hz

src/spice2x/games/iidx/iidx.cpp

@@ -67,6 +67,8 @@ namespace games::iidx {
     std::optional<std::string> SOUND_OUTPUT_DEVICE = std::nullopt;
     std::optional<std::string> SOUND_OUTPUT_DEVICE_IN_EFFECT = std::nullopt;
     std::optional<std::string> ASIO_DRIVER = std::nullopt;
+    uint32_t TT_DELAY_P1 = 0;
+    uint32_t TT_DELAY_P2 = 0;
     uint8_t DIGITAL_TT_SENS = 4;
     std::optional<std::string> SUBSCREEN_OVERLAY_SIZE = std::nullopt;
     std::optional<std::string> SCREEN_MODE = std::nullopt;
@@ -781,7 +783,26 @@ namespace games::iidx {
         }
 
         // return higher 8 bit
-        return (uint8_t) (ret_value >> 2);
+        uint8_t result = (uint8_t) (ret_value >> 2);
+
+        // delay
+        if ((player == 0 && TT_DELAY_P1 > 0) ||
+            (player == 1 && TT_DELAY_P2 > 0)) {
+
+            static std::queue<uint8_t> delay_queue[2];
+            auto &queue = delay_queue[player];
+
+            const auto max_size =
+                static_cast<size_t>((player == 0) ? TT_DELAY_P1 : TT_DELAY_P2) + 1;
+
+            queue.push(result);
+            while (queue.size() > max_size) {
+                queue.pop();
+            }
+            result = queue.front();
+        }
+
+        return result;
     }
 
     unsigned char get_slider(uint8_t slider) {

src/spice2x/games/iidx/iidx.h

@@ -31,6 +31,8 @@ namespace games::iidx {
     extern bool NATIVE_TOUCH;
     extern std::optional<std::string> SOUND_OUTPUT_DEVICE;
     extern std::optional<std::string> ASIO_DRIVER;
+    extern uint32_t TT_DELAY_P1;
+    extern uint32_t TT_DELAY_P2;
     extern uint8_t DIGITAL_TT_SENS;
     extern std::optional<std::string> SUBSCREEN_OVERLAY_SIZE;
     extern std::optional<std::string> SCREEN_MODE;