Requested changes

-Remove g_displaylevel/setNotificationLevel function
-Add extern "C"
-Remove averaging
-Reorder arguments

More fixes

-Added BMK_return_t (result + possible error)
-Correct comment'
-Nullcheck ctx, dctx when allocated
-Remove extra assert

tests/paramgrill.c

@@ -170,10 +170,10 @@ BMK_benchParam(BMK_result_t* resultPtr,
                ZSTD_CCtx* ctx, ZSTD_DCtx* dctx, 
                const ZSTD_compressionParameters cParams) {
 
-    *resultPtr = BMK_benchMem(srcBuffer,srcSize, "File", 0, &srcSize, 1, 
-        NULL, 0, &cParams, ctx, dctx, 0);
 
-    return 0;
+    BMK_return_t res = BMK_benchMem(srcBuffer,srcSize, &srcSize, 1, 0, &cParams, NULL, 0, ctx, dctx, 0, "File");
+    *resultPtr = res.result;
+    return res.errorCode;
 }
 
 static void BMK_printWinner(FILE* f, U32 cLevel, BMK_result_t result, ZSTD_compressionParameters params, size_t srcSize)