ZSTD_maxCLevel() is promoted to "stable" API (#254, by @FrancescAlted)

lib/compress/zstd_compress.c

@@ -2767,7 +2767,7 @@ ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
 
 #define ZSTD_DEFAULT_CLEVEL 1
 #define ZSTD_MAX_CLEVEL     22
-unsigned ZSTD_maxCLevel(void) { return ZSTD_MAX_CLEVEL; }
+int ZSTD_maxCLevel(void) { return ZSTD_MAX_CLEVEL; }
 
 static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEVEL+1] = {
 {   /* "default" */