merge multi threading to master branch

- updated zstd to latest devel release
- lz4, lz5 and zstd is included now
- all three support threading

C/zstd/zstd_v07.c

@@ -3690,7 +3690,12 @@ size_t ZSTDv07_execSequence(BYTE* op,
             op = oLitEnd + length1;
             sequence.matchLength -= length1;
             match = base;
+            if (op > oend_w) {
+              memmove(op, match, sequence.matchLength);
+              return sequenceLength;
+            }
     }   }
+    /* Requirement: op <= oend_w */
 
     /* match within prefix */
     if (sequence.offset < 8) {