os_support: fix misleading comments

cherry-picked from speexdsp 86779a06f6500d041573d6252d4971d3bfcb4b18

celt/os_support.h

@@ -67,18 +67,18 @@ static OPUS_INLINE void opus_free (void *ptr)
 }
 #endif
 
-/** Copy n bytes of memory from src to dst. The 0* term provides compile-time type checking  */
+/** Copy n elements from src to dst. The 0* term provides compile-time type checking  */
 #ifndef OVERRIDE_OPUS_COPY
 #define OPUS_COPY(dst, src, n) (memcpy((dst), (src), (n)*sizeof(*(dst)) + 0*((dst)-(src)) ))
 #endif
 
-/** Copy n bytes of memory from src to dst, allowing overlapping regions. The 0* term
+/** Copy n elements from src to dst, allowing overlapping regions. The 0* term
     provides compile-time type checking */
 #ifndef OVERRIDE_OPUS_MOVE
 #define OPUS_MOVE(dst, src, n) (memmove((dst), (src), (n)*sizeof(*(dst)) + 0*((dst)-(src)) ))
 #endif
 
-/** Set n elements of dst to zero, starting at address s */
+/** Set n elements of dst to zero */
 #ifndef OVERRIDE_OPUS_CLEAR
 #define OPUS_CLEAR(dst, n) (memset((dst), 0, (n)*sizeof(*(dst))))
 #endif