add chipmunk physics package

How do I know the test ran successfully?

```
$ make chipmunk
[target]   i686-pc-mingw32.static with 1 goal from command line
[build]    chipmunk
[done]     chipmunk
```
Can you try to add shared build support for chipmunk? From the flags it looks pretty easy:

```
$(if $(BUILD_STATIC), \
    -DBUILD_SHARED=OFF \
    -DBUILD_STATIC=ON \
    -DINSTALL_STATIC=ON, \
    -DBUILD_SHARED=ON \
    -DBUILD_STATIC=OFF \
    -DINSTALL_STATIC=OFF)
```

Please remember to always check if the shared builds are working before submitting it: https://github.com/mxe/mxe/wiki/Adding-Shared-Support-to-Packages#pre-commit-checklist