libstore: remove StorePath::random

It was only used for impure derivations, which were finally removed in commit
be07629820. Delete the unused function.

Change-Id: I6a6a696481711f68a8c3ea7eac7978fcf5884cce

lix/libstore/path.cc

@@ -1,7 +1,5 @@
 #include "lix/libstore/store-api.hh"
 
-#include <sodium.h>
-
 namespace nix {
 
 static void checkName(std::string_view path, std::string_view name)
@@ -62,13 +60,6 @@ bool StorePath::isDerivation() const
 
 StorePath StorePath::dummy("ffffffffffffffffffffffffffffffff-x");
 
-StorePath StorePath::random(std::string_view name)
-{
-    Hash hash(HashType::SHA1);
-    randombytes_buf(hash.hash, hash.hashSize);
-    return StorePath(hash, name);
-}
-
 StorePath Store::parseStorePath(std::string_view path) const
 {
     auto p = canonPath(std::string(path));

lix/libstore/path.hh

@@ -72,8 +72,6 @@ public:
     }
 
     static StorePath dummy;
-
-    static StorePath random(std::string_view name);
 };
 
 typedef std::set<StorePath> StorePathSet;