Actualize project root directories

This solves the problem of changing path spelling on platforms with case-
insensitive filesystems.

For example, you may build a project in the current working directory without
specifying any paths. This means the current working directory will be used as
the project's root. On Windows this could be C:\x.

Now you are building another project that imports the above project and you
specify config.import.x variable pointing to the above build. But you are lazy
to type capital C so you spell it as config.import.x=c:\x.

What happens now is the value from config.import.x is used as the project
root. And now it is a different spelling compared to your original build. This
is not a problem when the build system itself is concerned -- it is smart
enough to use case-insensitive comparison. However, we often use roots to
derive other things, say, -I options that we pass to compilers. And these
options are normally no longer treated as (case-insensitive) paths. If they
are hashed and the result stored in depdb, then we end up with rebuilds that
are triggered by changes from C:\ to c:\.

1 files changed, 3 insertions, 3 deletions

diff --git a/build2/file.cxx b/build2/file.cxx
index 155c8e6..a70c97a 100644
--- a/build2/file.cxx
+++ b/build2/file.cxx
@@ -664,7 +664,7 @@ namespace build2
 
     const dir_path& d (cast<dir_path> (l));
     dir_path out_root (root.out_path () / d);
-    out_root.normalize ();
+    out_root.normalize (); // No need to actualize (d is a bunch of ..)
 
     // src_root is a bit more complicated. Here we have three cases:
     //
@@ -692,7 +692,7 @@ namespace build2
         else // #1
         {
           dir_path src_root (root.src_path () / d);
-          src_root.normalize ();
+          src_root.normalize (); // No need to actualize (as above).
           v = move (src_root);
         }
       }
@@ -855,7 +855,7 @@ namespace build2
 
       if (auto l = iroot[var])
       {
-        out_root = cast<dir_path> (l);
+        out_root = cast<dir_path> (l); // Normalized and actualized.
         config::save_variable (iroot, var); // Mark as part of configuration.
       }
       else