We don't need them, but GHC API users might.

Patch from monoidal

Patch from Stephen Blackheath.

This is sometimes needed when cross-compiling, as some packages may be
built in stage 0 but not stage 1.

In order to make everything work out, this also removes the requirement
that the build-dirs are in dependency order

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

Doesn't look like it causes any failures in the full test suite, so
presumably it's fine!

Patch from Stephen Blackheath

Apparently ios doesn't understand .type %function.

They're both the same register, and Linux seems happy with both,
but ios only accepts r11.

Apparently ios only understands .globl, but Linux appears to understand
both.

Based on patch from Stephen Blackheath.

We now use the 'host' to determine whether stage0 builds terminfo,
and 'target' to determine whether stage1 does.

We don't build it if the platform is either Windows or ios.

This makes the build system a little simpler, and in particular
will make it easier to handle the changes needed for cross-compilation.