This also fixes a missing header in the SDK that rtags needs to work
properly. The underlying cause is that C++ headers got shuffled around a
lot in libc++ 3.8 (I believe) and became more standards-compliant, which
led to a lot of C-compatible passthrough header files being added to it
like math.h, which defines some C++-compatible versions of standard
functions like signbit, while #include_next'ing the system math.h. In
this case, including the SDK was stuffing another math.h in front of the
libc++ shim, which led to all sorts of mysterious failures.
This is a slightly less ambitious version of the (now reverted) commit
377cef8d16, which had a bunch of issues
that I don't have time to resolve right now.
The SDK includes cups header files, but not the libraries. The
`nixpkgs.cups` definition doesn't build on darwin due to the SDK being
too old. This change symlinks the system cups libraries into the old
SDK.
The AVFoundation framework uses a relative path that presumes that
CoreGraphics is a child framework of ApplicationServices. It is not in
the 10.9 SDK.
This patch makes it one by tweaking the framework derivation generator
with special support to address this problem.
