Staged installs support.

[ioga]

Some package managers (f.e., gentoo portage) require staged install support:
i.e. installation of files into some temporary location (prefix).
This changeset adds support of that feature via DESTDIR variable.
Also see https://www.gnu.org/prep/standards/html_node/DESTDIR.html .

Related haxelib commit: HaxeFoundation/haxelib#128

[waneck]

The changes seem ok. But is there any particular reason to go through the trouble of making a symbolic link to haxelib_script.sh , only to make it readlink -f to get its path? What was wrong with generating the script on-the-fly at the install?

[ioga]

@waneck
In the autogenerated script you'd have a fixed absolute path of haxelib classpath, so it could be run only if it's installed in that fixed location (i.e. /usr/lib/haxe).

Symlink can be installed to any place, and it would work properly as long as it valid.
readlink -f resolves the symlink, which gets you the location of haxelib_src installation, and you don't need to worry about its install path any more.

Also, I believe it's not very pretty to have haxelib (which is a submodule, i.e. intended to be more independent) implementation detail (i.e. script body) in the install section of haxe makefile.

Does it make sense?

[andyli]

I've just committed it without the haxelib change.
haxelib is fragile and I don't want to break anything. It will probably be improved when addressing HaxeFoundation/haxelib#172.