added sparta/include dir to headers for cmake builds (#337)
added sparta/include dir to headers for cmake builds (#337)

Summary:
This commit adds the embedded `sparta/include` dir to the header searchpath
for cmake builds as a fix for errors locating `MonotonicFixpointIterator.h`
(and possibly other) includes.

Without this I see errors like below during build:

```
../libredex/CallGraph.h:15:10: fatal error: 'MonotonicFixpointIterator.h' file not found
```
Pull Request resolved: https://github.com/facebook/redex/pull/337

Reviewed By: int3

Differential Revision: D9182961

Pulled By: thezhangwei

fbshipit-source-id: 93227315554635d59cb478c0c759cc1832762ca7

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex