new frame format, allowing custom window size

lib/common/zstd_internal.h

@@ -81,8 +81,8 @@
 #define BIT1   2
 #define BIT0   1
 
-#define ZSTD_WINDOWLOG_ABSOLUTEMIN 12
-static const size_t ZSTD_fcs_fieldSize[4] = { 0, 1, 2, 8 };
+#define ZSTD_WINDOWLOG_ABSOLUTEMIN 10
+static const size_t ZSTD_fcs_fieldSize[4] = { 0, 2, 4, 8 };
 static const size_t ZSTD_did_fieldSize[4] = { 0, 1, 2, 4 };
 
 #define ZSTD_BLOCKHEADERSIZE 3   /* C standard doesn't allow `static const` variable to be init using another `static const` variable */