This changes cygwin stdenv, but I don't think it will hurt much people.
This allows mkDerivation to get "dontRebase=true" to skip the usual cygwin
rebase. This is required, if we are using this stdenv to build DLLs for win32
inside x86_64-cygwin, because /bin/rebase crashes at finding an arch mismatch.
Additionally, we don't need any rebase for libraries built by visual studio and
meant for visual studio (my use case).
I'm using nix in x86_64-cygwin to build libraries with visual studio, both for
x86_64 and x86.
* Some fetchurl-related refactoring. The `realCurl' attribute is
gone, `curl' is the real thing. To prevent an infinite recursion in
`fetchurl' (because it depends on curl and building curl needs
fetchurl), curl and its dependencies (openssl, zlib, perl) use
`fetchurlBoot', which is the fetchurl used by the previous bootstrap
phase (e.g. the statically linked version of curl for
stdenv-linux). So as a result you can use https:// urls almost
everywhere.
There's also some hackery to prevent a different curl from being
built in every stdenv-linux bootstrap phase (namely the
stdenv.fetchurl attribute which allows fetchurl to be overriden
everywhere).
svn path=/nixpkgs/trunk/; revision=11905
(ideally, this should be the other way around, but I have no idea how
many packages will break if we enable shared libraries by default)
svn path=/nixpkgs/trunk/; revision=5923
