fixed one race scenario

lib/compress/zstdmt_compress.c

diff --git a/lib/compress/zstdmt_compress.c b/lib/compress/zstdmt_compress.c
index 91f1580..68f9111 100644
--- a/lib/compress/zstdmt_compress.c
+++ b/lib/compress/zstdmt_compress.c
@@ -837,6 +837,7 @@
     job->cSize += lastCBlockSize;
     job->consumed = job->src.size;  /* when job->consumed == job->src.size , compression job is presumed completed */
     if (job->flush_mutex != NULL) {
+        assert(job->flush_cond != NULL);
         ZSTD_pthread_mutex_unlock(&job->job_mutex);
         ZSTD_PTHREAD_MUTEX_LOCK(job->flush_mutex);
         ZSTD_pthread_cond_signal(job->flush_cond);   /* warns some more data is ready to be flushed */
@@ -1603,8 +1604,6 @@
                 DEBUGLOG(5, "dstBuffer released");
                 mtctx->jobs[wJobID].dstBuff = g_nullBuffer;
                 mtctx->jobs[wJobID].cSize = 0;   /* ensure this job slot is considered "not started" in future check */
-                mtctx->jobs[wJobID].flush_mutex = NULL;
-                mtctx->jobs[wJobID].flush_cond = NULL;
                 mtctx->consumed += srcSize;
                 mtctx->produced += cSize;
                 mtctx->doneJobID++;

tests/zstreamtest.c

diff --git a/tests/zstreamtest.c b/tests/zstreamtest.c
index b8290fe..e87a523 100644
--- a/tests/zstreamtest.c
+++ b/tests/zstreamtest.c
@@ -2900,7 +2900,7 @@
         U32 lseed;
         int opaqueAPI;
         const BYTE* srcBuffer;
-        size_t totalTestSize, totalGenSize, cSize;
+        size_t totalTestSize, totalGenSize, cSize=0;
         XXH64_state_t xxhState;
         U64 crcOrig;
         U32 resetAllowed = 1;