rust-cpython: fix build for MacOSX
MacOSX needs special link flags. Quoting the README of rust-cpython:
create a `.cargo/config` with the following content:
```
[target.x86_64-apple-darwin]
rustflags = [
"-C", "link-arg=-undefined",
"-C", "link-arg=dynamic_lookup",
]
```
This is tested with Python 2.7 (Anaconda install) and Python 3
(Homebrew install)
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false