kernel32: Fix GetVolumeInformation[AW] to require trailing \.

dlls/kernel32/tests/volume.c

@@ -287,7 +287,6 @@ static void test_GetVolumeInformationA(void)
     /* check for error on no trailing \   */
     ret = pGetVolumeInformationA(Root_Dir0, vol_name_buf, vol_name_size, NULL,
             NULL, NULL, fs_name_buf, fs_name_len);
-todo_wine
     ok(!ret && GetLastError() == ERROR_INVALID_NAME,
         "GetVolumeInformationA w/o '\\' did not fail, last error %u\n", GetLastError());
 

dlls/kernel32/volume.c

@@ -526,7 +526,7 @@ BOOL WINAPI GetVolumeInformationW( LPCWSTR root, LPWSTR label, DWORD label_len,
     }
     else
     {
-        if (!root[0] || root[1] != ':')
+        if (!root[0] || root[1] != ':' || root[lstrlenW(root)-1] != '\\' )
         {
             SetLastError( ERROR_INVALID_NAME );
             return FALSE;