Update lexer-crlf-line-endings-string-literal-doc-comment.rs

Author: GuillaumeGomez

tests/ui/lexer/lexer-crlf-line-endings-string-literal-doc-comment.rs

@@ -1,5 +1,6 @@
 //@ run-pass
 //@ reference: input.crlf
+//@ ignore-backends: gcc
 // ignore-tidy-cr
 // ignore-tidy-cr (repeated again because of tidy bug)
 // license is ignored because tidy can't handle the CRLF here properly.
@@ -36,3 +37,4 @@ literal";
     let source = include_str!("lexer-crlf-line-endings-string-literal-doc-comment.rs");
     assert!(source.contains("string\r\nliteral"));
 }
+