Fix FS#9577 - SNES player missing tracks on certain SPCs

Affected BRR cached waveforms but not realtime BRR decode as far as
I could ascertain. BRR cached waves required loop points to be inside
the initial waveform but this change removes that restriction.

Change-Id: I0ef4db720e5c28bd7b2fb9ae255d27c0a7213f79

lib/rbcodec/codecs/libspc/spc_codec.h

@@ -292,6 +292,7 @@ struct voice_wave_t
     int loop;              /* length of looping area */
     unsigned block_header; /* header byte from current BRR block */
     uint8_t const* addr;   /* BRR waveform address in RAM */
+    unsigned loop_addr;    /* Loop address in RAM */
 };
 #else /* !SPC_BRRCACHE */
 struct voice_wave_t