CMAKE build fails on Ubuntu 14.04

[slimsag]

stephen@stephen-Inspiron-N5110:~/Desktop/Chipmunk2D$ make
[  1%] Building C object src/CMakeFiles/chipmunk.dir/cpSpaceDebug.c.o
/home/stephen/Desktop/Chipmunk2D/src/cpSpaceDebug.c:22:39: fatal error: chipmunk/chipmunk_private.h: No such file or directory
 #include "chipmunk/chipmunk_private.h"
                                       ^
compilation terminated.
make[2]: *** [src/CMakeFiles/chipmunk.dir/cpSpaceDebug.c.o] Error 1
make[1]: *** [src/CMakeFiles/chipmunk.dir/all] Error 2
make: *** [all] Error 2

[mrozbarry]

This error is also apparent on Arch Linux from git 6fd3b92.

[mxnemu]

Temporary workaround to make it build, until #85 or #89 gets merged:

cd src
ln -s ../include/chipmunk/ chipmunk