test: temporary fix for UNC path parsing issue (alexcrichton#331)

Prepend `c:` so that it won't be treated as UNC path.

See rust-lang/rust#100833 for more.

tests/all.rs

@@ -579,10 +579,21 @@ fn extracting_malicious_tarball() {
  t!(a.append(&header, io::repeat(1).take(1)));
  };
  append("/tmp/abs_evil.txt");
- append("//tmp/abs_evil2.txt");
+ // std parse `//` as UNC path, see rust-lang/rust#100833
+ append(
+ #[cfg(not(windows))]
+ "//tmp/abs_evil2.txt",
+ #[cfg(windows)]
+ "C://tmp/abs_evil2.txt",
+ );
  append("///tmp/abs_evil3.txt");
  append("/./tmp/abs_evil4.txt");
- append("//./tmp/abs_evil5.txt");
+ append(
+ #[cfg(not(windows))]
+ "//./tmp/abs_evil5.txt",
+ #[cfg(windows)]
+ "C://./tmp/abs_evil5.txt",
+ );
  append("///./tmp/abs_evil6.txt");
  append("/../tmp/rel_evil.txt");
  append("../rel_evil2.txt");