Restore line endings in a test

In #28864, @aarzee submitted some whitespace fixes. I r+'d it. But
@retp998 noticed[1] that this file is explicitly a test of this kind of
whitespace, and so I shouldn't have changed it. This restores the old
line endings.

1: https://github.com/rust-lang/rust/pull/28864#discussion_r41332279

src/test/run-pass/lexer-crlf-line-endings-string-literal-doc-comment.rs

@@ -1,7 +1,7 @@
 // ignore-tidy-cr ignore-license
 // ignore-tidy-cr (repeated again because of tidy bug)
 // license is ignored because tidy can't handle the CRLF here properly.
-
+
 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
@@ -11,33 +11,33 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
-
+
 // NB: this file needs CRLF line endings. The .gitattributes file in
 // this directory should enforce it.
-
+
 // ignore-pretty
-
+
 /// Doc comment that ends in CRLF
 pub fn foo() {}
-
+
 /** Block doc comment that
  *  contains CRLF characters
  */
 pub fn bar() {}
-
+
 fn main() {
     let s = "string
 literal";
     assert_eq!(s, "string\nliteral");
-
+
     let s = "literal with \
              escaped newline";
     assert_eq!(s, "literal with escaped newline");
-
+
     let s = r"string
 literal";
     assert_eq!(s, "string\nliteral");
-
+
     // validate that our source file has CRLF endings
     let source = include_str!("lexer-crlf-line-endings-string-literal-doc-comment.rs");
     assert!(source.contains("string\r\nliteral"));