* Changed a few version(linux) blocks to version(Posix).

* Changed some declarations from explicit to auto.
* Changed "mkdir --parents" in Makefile to "mkdir -p" since OSX doesn't support the long version.
* REMAINING ISSUE: The "ln -sf" for installing the libraries at the end will fail if the DMD installation point is not owned by the user performing the build.  A "sudo ln..." fixes this, but it still may not be ideal to have a system-level link to a user-level file.  This should probably simply be copied instead.  Also, this copy should perhaps be done manually or in an "install" step, since a user may want to build Phobos and test it out without affecting other users.

std/stdio.d

@@ -864,7 +864,7 @@ $(D Range that locks the file and allows fast writing to it. */
                                     handle);
                         }
                     }
-                    else version (linux)
+                    else version (Posix)
                     {
                                  FPUTWC(c, handle);
                     }