Initial version of ice.
Renamed LICENSE -> LICENSE.md
Generate extern and struct item defns into separate headers.

This replaces the existing .lst files, and makes it much easier
to integrate with frozen libraries with existing applications
where Python is embedded, but does not run as main (such as
gdb).
Add 'ice/' from commit '6d83c302fbdc07e902035b9288a5009da4657cf4'

git-subtree-dir: ice
git-subtree-mainline: 1ad071dbb9910f58dbb27a678ba468ced99b790f
git-subtree-split: 6d83c302fbdc07e902035b9288a5009da4657cf4
Sort imports alphabetically
Add root_dir_abs to default config.
Python should use host_lib_configure, not cross_configure
Force lib-dynload to exist.

Python gets confused at startup if lib-dynload doesn't exist, so
we force it to exist, even though it doesn't contain any real files.
.dummy is added since some archivers/revision control systems
don't track directories, only files; it is important we don't lose
the directory.
Improve gdb build; depend on python.

This provides initial support for compiling gdb against the
xyz Python package. Basic functionality works, however
there is likely some corner cases that need more work.