[XMA] Fix stall detection false positive in Work loop

Stall detection was triggering during multi-pass subframe consumption
(e.g. stereo with subframe_decode_count < total subframes), breaking
audio looping in games like Tomb Raider. Now only detects a stall when
no subframes were pending, so Consume-only iterations aren't mistaken
for no-progress cycles. Fixes Halo 4 without regressing Tomb Raider.

src/xenia/apu/xma_context_new.cc

@@ -176,6 +176,9 @@ bool XmaContextNew::Work() {
         data.output_buffer_valid, data.subframe_decode_count,
         data.output_buffer_padding);
 
+    const uint32_t pre_decode_offset = data.input_buffer_read_offset;
+    const uint8_t pre_remaining_subframes = current_frame_remaining_subframes_;
+
     Decode(&data);
     Consume(&output_rb, &data);
 
@@ -185,6 +188,21 @@ bool XmaContextNew::Work() {
           id(), data.IsAnyInputBufferValid(), data.error_status);
       break;
     }
+
+    // If Decode didn't advance the read offset and produced no new frame,
+    // we can't make progress. Break to avoid spinning.
+    // Only check when there were no pending subframes — if we entered this
+    // iteration with subframes remaining, Decode() intentionally skipped
+    // (offset unchanged) while Consume() drained the frame.
+    if (pre_remaining_subframes == 0 &&
+        data.input_buffer_read_offset == pre_decode_offset &&
+        current_frame_remaining_subframes_ == 0) {
+      XELOGAPU(
+          "XmaContext {}: Decode stalled at offset {} (no progress), "
+          "waiting for next buffer",
+          id(), pre_decode_offset);
+      break;
+    }
   }
 
   data.output_buffer_write_offset =