zstd_opt.h: improved price function

lib/common/zstd_internal.h

@@ -222,6 +222,7 @@ typedef struct {
     U32  log2litSum;
     U32  log2offCodeSum;
     U32  factor;
+    U32  staticPrices;
     U32  cachedPrice;
     U32  cachedLitLength;
     const BYTE* cachedLiterals;