gettext: always use UTF-8 on native Windows

Git on native Windows exclusively uses UTF-8 for console output (both with
mintty and native console windows). Gettext uses setlocale() to determine
the output encoding for translated text, however, MSVCRT's setlocale()
doesn't support UTF-8. As a result, translated text is encoded in system
encoding (GetAPC()), and non-ASCII chars are mangled in console output.

Use gettext's bind_textdomain_codeset() to force the encoding to UTF-8 on
native Windows.

Signed-off-by: Karsten Blees <blees@dcon.de>

gettext.c

@@ -12,6 +12,8 @@
 #	include <libintl.h>
 #	ifdef HAVE_LIBCHARSET_H
 #		include <libcharset.h>
+#	elif defined GIT_WINDOWS_NATIVE
+#		define locale_charset() "UTF-8"
 #	else
 #		include <langinfo.h>
 #		define locale_charset() nl_langinfo(CODESET)