Wide string conversion with multibyte chars and locale + concatenation

 cl.exe 

Current locale: de-DE
Original string: 測試
	ret = 0, bytesConverted = 7, output = 測試
Concatenated string: 測試-concatenated
Original string: αβ
	ret = 0, bytesConverted = 5, output = αβ
Concatenated string: αβ-concatenated
Original string: �	ret = 42, bytesConverted = 0, output = 
Concatenated string: -concatenated