GitLab

These are some of the changes to HMake that Malcolm and I had
talked about some time back.  The PPSuffixHandler is meant to
allow extendability.  Build will probably have to take a list
of these as an argument.

* Add --with-hc-pkg flag to specify the hc-pkg path separately from
  the compiler
* #include config.h where necessary to get the definition of
  mingw32_TARGET_OS.
* Flush stdout before writing to stderr on Windows (gets some
  messages in the right order).

Bugfix. Since the .o files are only added to library, it will grow after each build. The fix is to remove libHS*.a file before build.

Added mkLibDir & mkBinDir functions. This helps to use the same paths in all places. Fixes a bug under Windows.

Use --update-package option instead of --add-package since the package can be registered multiple times.