Backend: Create "backend" folder

similar to the "frontend" folder

src/backend/x64/hostloc.cpp

@@ -0,0 +1,23 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2016 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#include <xbyak.h>
+
+#include "backend/x64/hostloc.h"
+
+namespace Dynarmic::BackendX64 {
+
+Xbyak::Reg64 HostLocToReg64(HostLoc loc) {
+    ASSERT(HostLocIsGPR(loc));
+    return Xbyak::Reg64(static_cast<int>(loc));
+}
+
+Xbyak::Xmm HostLocToXmm(HostLoc loc) {
+    ASSERT(HostLocIsXMM(loc));
+    return Xbyak::Xmm(static_cast<int>(loc) - static_cast<int>(HostLoc::XMM0));
+}
+
+} // namespace Dynarmic::BackendX64