fix: remove unnecessary files

Author: SpringMT

Rakefile

@@ -17,6 +17,12 @@ task :default => [:clobber, :compile, :spec]
 
 desc 'Sync zstd libs dirs to ext/zstdruby/libzstd'
 task :zstd_update do
-  FileUtils.rm_r('ext/zstdruby/libzstd')
-  FileUtils.cp_r('zstd/lib', 'ext/zstdruby/libzstd')
+  FileUtils.rm_r("ext/zstdruby/libzstd")
+  FileUtils.mkdir_p("ext/zstdruby/libzstd")
+  ["common", "compress", "decompress", "dictBuilder"].each do |dir|
+    FileUtils.cp_r("zstd/lib/#{dir}", "ext/zstdruby/libzstd/#{dir}")
+  end
+  FileUtils.cp_r('zstd/lib/zdict.h', 'ext/zstdruby/libzstd')
+  FileUtils.cp_r('zstd/lib/zstd.h', 'ext/zstdruby/libzstd')
+  FileUtils.cp_r('zstd/lib/zstd_errors.h', 'ext/zstdruby/libzstd')
 end