Remove unused #include.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@302719 91177308-0d34-0410-b5e6-96231b3b80d8

ELF/Threads.h

@@ -62,7 +62,6 @@
 #include "Config.h"
 
 #include "lld/Core/Parallel.h"
-#include <algorithm>
 #include <functional>
 
 namespace lld {