fix #944 : ZSTDMT with large files and dictionary now works correctly

windowLog is now enforced from provided compression parameters,
instead of being copied blindly from `cdict`
where it could be smaller.

also :
- fix a minor bug in zstreamtest --mt : advanced parameters must be set before init
- changed advanced parameter name to ZSTDMT_jobSize

lib/compress/zstd_compress_internal.h

@@ -447,6 +447,7 @@ ZSTD_compressionParameters ZSTD_getCParamsFromCDict(const ZSTD_CDict* cdict);
 size_t ZSTD_compressBegin_advanced_internal(ZSTD_CCtx* cctx,
                                     const void* dict, size_t dictSize,
                                     ZSTD_dictMode_e dictMode,
+                                    const ZSTD_CDict* cdict,
                                     ZSTD_CCtx_params params,
                                     unsigned long long pledgedSrcSize);