Fix missing includes

Source/Core/AudioCommon/OpenALStream.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2+
 // Refer to the license.txt file included.
 
+#include <climits>
 #include <cstring>
 #include <thread>
 

Source/Core/Common/x64CPUDetect.cpp

@@ -12,6 +12,8 @@
 #ifndef _WIN32
 
 #ifdef __FreeBSD__
+#include <unistd.h>
+
 #include <machine/cpufunc.h>
 #include <sys/types.h>
 #endif

Source/Core/Core/FifoPlayer/FifoDataFile.cpp

@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
+#include <cstring>
 #include <string>
 
 #include "Common/FileUtil.h"

Source/Core/Core/PowerPC/JitCommon/JitCache.h

@@ -6,6 +6,7 @@
 
 #include <array>
 #include <bitset>
+#include <cstring>
 #include <functional>
 #include <map>
 #include <memory>