semantic change: allow reaching into parent directories in paths

This allows generating build files in a subdirectory of your source tree.
- Change CanonicalizePath to accept this.
- CanonicalizePath no longer has an error condition, so change it to a void
  function.

I profiled the result against Chrome and it might be ~100ms slower, but that
might just be Chrome's size working against me.  In any case I think there
are lower-hanging performance fruit elsewhere.

1 files changed, 1 insertions, 2 deletions

diff --git a/src/parsers.cc b/src/parsers.cc
index 7c08179..2235ba2 100644
--- a/src/parsers.cc
+++ b/src/parsers.cc
@@ -516,8 +516,7 @@ bool ManifestParser::ParseEdge(string* err) {
       if (!eval.Parse(*i, &eval_err))
         return tokenizer_.Error(eval_err, err);
       string path = eval.Evaluate(env);
-      if (!CanonicalizePath(&path, err))
-        return false;
+      CanonicalizePath(&path);
       *i = path;
     }
   }