filesys.test: fixes for copy-file test on MinGW

In the copy-file test, is uses call-with-input-file and get-string-all
to retrieve file contents. Since the file is not opened in binary mode,
CRLF line ending may be added when writing and then reading the string
back from the filesystem.

* test-suite/tests/filesys.test (normalize-newlines): new helper function
  ("copy file: copy-file dest content"): pass even if CRLF line endings
  are added
  ("copy file: read only dest"): handle posibility of geteuid not
  being defined

test-suite/tests/filesys.test

@@ -46,6 +46,18 @@
       (chmod file (logior (stat:mode (stat file)) #o200)))
     (delete-file file)))
 
+(define (normalize-newlines s)
+  "Returns a copy of the input string, replacing any #\return #\newline
+pairs with #\newline."
+  (let loop ((i 0) (result '()))
+    (if (< i (string-length s))
+        (if (and (< (+ i 1) (string-length s))
+                 (char=? (string-ref s i) #\return)
+                 (char=? (string-ref s (+ i 1)) #\newline))
+            (loop (+ i 2) (cons #\newline result))
+            (loop (+ i 1) (cons (string-ref s i) result)))
+        (list->string (reverse result)))))
+
 ;;;
 ;;; copy-file
 ;;;
@@ -69,8 +81,14 @@
        (with-test-prefix "successful copy"
          (copy-file src dest)
          (pass-if-equal "copy-file dest content" msg
-           (call-with-input-file dest get-string-all)))
-       (unless (zero? (geteuid))
+	   ;; Since call-with-input-file is always text mode, it may have
+	   ;; \r\n on MinGW.
+           (normalize-newlines
+            (call-with-input-file dest get-string-all))))
+       ;; Checking for a geteuid of zero is testing of the user
+       ;; is root, making the chmod to read-only meaningless.  geteuid is
+       ;; not defined in MinGW.
+       (unless (and (defined? 'geteuid) (zero? (geteuid)))
          (with-test-prefix "read only dest"
            (chmod dest #o444)
            (with-exception-handler