zstd: Add 1.3.8 (#11012)

var/spack/repos/builtin/packages/zstd/package.py

@@ -14,6 +14,7 @@ class Zstd(MakefilePackage):
     homepage = "http://facebook.github.io/zstd/"
     url      = "https://github.com/facebook/zstd/archive/v1.1.2.tar.gz"
 
+    version('1.3.8', '90d902a1282cc4e197a8023b6d6e8d331c1fd1dfe60f7f8e4ee9da40da886dc3')
     version('1.3.0', '888660a850e33c2dcc7c4f9d0b04d347')
     version('1.1.2', '4c57a080d194bdaac83f2d3251fc7ffc')