Misc implementations and fixes. (#250)

* Implement `sceKernelFtruncate` and `sceKernelUnlink`.

* Remove unused variable.

* Implement `sceKernelReserveVirtualRange`, misc fixes

* Fix `sceKernelReserveVirtualRange`.

* Add TODO on reserve

* Replace comment with assert.

* Add missing copyright header

* Add `UNREACHABLE` for `IOFile::Unlink`.

* Move NT API initialization out of the header

* Fix bug where files were always mapped as read only.

* `clang-format`

src/common/io_file.h

@@ -107,6 +107,8 @@ public:
              FileShareFlag flag = FileShareFlag::ShareReadOnly);
     void Close();
 
+    void Unlink();
+
     bool Flush() const;
     bool Commit() const;