Externals: Add libLZMA.

Externals/liblzma/common/hardware_cputhreads.c

@@ -0,0 +1,22 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       hardware_cputhreads.c
+/// \brief      Get the number of CPU threads or cores
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+
+#include "tuklib_cpucores.h"
+
+
+extern LZMA_API(uint32_t)
+lzma_cputhreads(void)
+{
+	return tuklib_cpucores();
+}