Windows process username() potential memory leak in case of error

[giampaolo]

...because the C implementation is a mess and does not properly cleanup resources as it should (via goto). In detail it's the token handle which is freed only assuming the previous instructions succeed and never return:

psutil/psutil/_psutil_windows.c

Line 1360 in 4c07213

CloseHandle(tokenHandle);

[giampaolo]

...also, Py_Unicode* return value is never checked, potentially leading to invalid data being returned:

psutil/psutil/_psutil_windows.c

Lines 1411 to 1417 in 4c07213

	#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
	py_unicode = PyUnicode_DecodeLocaleAndSize(
	fullName, _tcslen(fullName), "surrogateescape");
	#else
	py_unicode = PyUnicode_Decode(
	fullName, _tcslen(fullName), Py_FileSystemDefaultEncoding, "replace");
	#endif