Fix compling error in exercise 8 and solution 8

Solution:
1. Remove misplaced #endif

Exercise:
1. Remove extra #ifndef macro and misplaced #endif
2. Remove implementation of constructor, deconstructor and creator in
the arrowLocator header
3. Add missing headers in arrowLocator.cpp
4. Replace OpenMayaRender.mll with OpenMayaRender.lib in the linker
option.
Merge pull request #2 from iamsleepy/master

Fix compling error in exercise 8 and solution 8