Fix crash when more than one sound emitter use one sound source

It crashed when one sound emitter was reading from sound source file and
other emitter was destroying the handle of that file.

src/xrSound/SoundRender_Source.cpp

@@ -51,11 +51,11 @@ bool ov_can_continue_read(long res)
 
 void CSoundRender_Source::decompress(void* dest, u32 byte_offset, u32 size)
 {
-    std::lock_guard guard{ read_lock };
-
     if (!wave)
         attach();
 
+    std::lock_guard guard{ read_lock };
+
     // seek
     const auto sample_offset = ogg_int64_t(byte_offset / m_wformat.nBlockAlign);
     const u32 cur_pos = u32(ov_pcm_tell(&ovf));
@@ -145,21 +145,28 @@ constexpr ov_callbacks g_ov_callbacks =
 
 void CSoundRender_Source::attach()
 {
-    VERIFY(0 == wave);
-    if (wave)
-        return;
-    wave = FS.r_open(pname.c_str());
-    R_ASSERT3(wave && wave->length(), "Can't open wave file:", pname.c_str());
-    ov_open_callbacks(wave, &ovf, nullptr, 0, g_ov_callbacks);
+    std::lock_guard guard{ read_lock };
+    ++refs;
+    VERIFY(refs > 0);
+    if (refs == 1)
+    {
+        wave = FS.r_open(pname.c_str());
+        R_ASSERT3(wave && wave->length(), "Can't open wave file:", pname.c_str());
+        ov_open_callbacks(wave, &ovf, nullptr, 0, g_ov_callbacks);
+    }
 }
 
 void CSoundRender_Source::detach()
 {
-    if (wave)
+    std::lock_guard guard{ read_lock };
+    --refs;
+    if (refs == 0)
     {
         ov_clear(&ovf);
         FS.r_close(wave);
     }
+    if (refs < 0)
+        refs = 0;
 }
 
 bool CSoundRender_Source::LoadWave(pcstr pName, bool crashOnError)

src/xrSound/SoundRender_Source.h

@@ -12,6 +12,7 @@ class XRSOUND_API CSoundRender_Source final : public CSound_source
 
     OggVorbis_File ovf{};
     IReader* wave{};
+    int refs{};
     std::mutex read_lock;
 
     float fTimeTotal;