arm_types: Split out LocationDescriptor (#20)

This isn't really an ARM-specific type, since it's used to indicate a
Block location.

include/dynarmic/dynarmic.h

@@ -15,8 +15,8 @@
 
 namespace Dynarmic {
 
-namespace Arm {
-struct LocationDescriptor;
+namespace IR {
+class LocationDescriptor;
 }
 
 class Jit final {
@@ -76,7 +76,7 @@ public:
      * @param descriptor Basic block descriptor.
      * @return A string containing disassembly of the host machine code produced for the basic block.
      */
-    std::string Disassemble(const Arm::LocationDescriptor& descriptor);
+    std::string Disassemble(const IR::LocationDescriptor& descriptor);
 
 private:
     bool is_executing = false;