Fix GH-11141: Could not open input file: should be sent to stderr

I grepped for php_printf cases in main/ and sapi/ and converted the
cases which clearly indicate errors to fprintf(stderr, ...), like
suggested in the linked issue.

Closes GH-11163.

sapi/litespeed/lsapi_main.c

@@ -1347,7 +1347,7 @@ static int cli_main( int argc, char * argv[] )
                         php_request_shutdown( NULL );
                     }
                 } else {
-                    php_printf("Could not open input file: %s.\n", *p);
+                    fprintf(stderr, "Could not open input file: %s.\n", *p);
                 }
             } else {
                 cli_usage();