Update ZStd. Fixes an issue with Make 3.82 (facebook#8155)

Summary:
The previous version of ZStd doesn't build correctly with Make 3.82. Updating it resolves the issue.

jay-zhuang This also needs to be cherry-picked to:
1. 6.17.fb
2. 6.18.fb
3. 6.19.fb

Pull Request resolved: facebook#8155

Reviewed By: riversand963

Differential Revision: D27596460

Pulled By: ajkr

fbshipit-source-id: ac8492245e6273f54efcc1587346a797a91c9441

Makefile

@@ -2001,8 +2001,8 @@ SNAPPY_DOWNLOAD_BASE ?= https://github.com/google/snappy/archive
 LZ4_VER ?= 1.9.3
 LZ4_SHA256 ?= 030644df4611007ff7dc962d981f390361e6c97a34e5cbc393ddfbe019ffe2c1
 LZ4_DOWNLOAD_BASE ?= https://github.com/lz4/lz4/archive
-ZSTD_VER ?= 1.4.7
-ZSTD_SHA256 ?= 085500c8d0b9c83afbc1dc0d8b4889336ad019eba930c5d6a9c6c86c20c769c8
+ZSTD_VER ?= 1.4.9
+ZSTD_SHA256 ?= acf714d98e3db7b876e5b540cbf6dee298f60eb3c0723104f6d3f065cd60d6a8
 ZSTD_DOWNLOAD_BASE ?= https://github.com/facebook/zstd/archive
 CURL_SSL_OPTS ?= --tlsv1