cksum: Investigate the display strategy of valid UTF-8 but non-ASCII filenames

[RenjiSann]

(Found with fuzzer)

args: ["cksum", "file_rIÃ", "file_pGB(e"]                                                                                                     
Running test ["cksum", "file_rIÃ", "file_pGB(e"]                                                                                              
Test Type: cksum                                                                                                                              
Input: ["file_rIÃ", "file_pGB(e"]                                                                                                             
Rust stderr: file_rIÃ: No such file or directory                                                                                              
cksum: file_pGB(e: No such file or directory                                                                                                  
GNU stderr: 'file_rI'$'\303\203': No such file or directory                                                                                   
cksum: 'file_pGB(e': No such file or directory                                                                                                
Diff=                                                                                                                                         
-file_rIÃ: No such file or directory                                                                                                          
-cksum: file_pGB(e: No such file or directory                                                                                                 
+'file_rI'$'\303\203': No such file or directory                                                                                              
+cksum: 'file_pGB(e': No such file or directory                                                                                               
                                                                                                                                              
Discrepancy detected: stderr differs                                                                                                          
Test completed with discrepancies for cksum: ["file_rIÃ", "file_pGB(e"] 

3 things here :

• The Ä should be escaped, even so it is a valid UTF8 character.
• The first line doesn't get the cksum: prefix
• We also forget to quote the filename with )