Restore removed <algorithm> includes.

Turns out these were needed after all. For some reason, on Windows and
Mac, <algorithm> gets auto-included by something else so I don't notice
when it's missing, and MSVC's include dependency tracker doesn't see it
either.

Common/CPUDetect.cpp

@@ -35,6 +35,7 @@
 #include <cstdint>
 #include <memory.h>
 #include <set>
+#include <algorithm>
 
 #include "Common/Common.h"
 #include "Common/CPUDetect.h"