Remove obsolete Win32 AffinityBugWorkaround()

Reference miner exists for testnet-in-a-box type situations, and as a
reference.  We don't care enough about highly optimized internal
mining to keep workarounds like this.

src/main.cpp

@@ -3361,8 +3361,6 @@ void static BitcoinMiner(CWallet *pwallet)
 
     while (fGenerateBitcoins)
     {
-        if (AffinityBugWorkaround(ThreadBitcoinMiner))
-            return;
         if (fShutdown)
             return;
         while (vNodes.empty() || IsInitialBlockDownload())