Update EASTL_Project_Integration.md

[JochenJankowai]

Some info for building with CMake was outdated.

• Adding the subdirectory will set up include paths for the packages. No need to do it explicitly.
• Set include directory per target.
• EASTL_LIBRARY is now called EASTL.
• Two new operator overloads are required.

[grojo-ea]

Hello,

Thanks for updating these!

The change looks good to me. Could you please fill out our CLA form with your info so we can merge this change?

[JochenJankowai]

Done!

[vchuynh]

Followed your updated integration guide and got EASTL to build with a couple issues. For the target_link_libraries part, shouldn't it just be EASTL? That's what I needed to do for mine to build. The EASTL variable isn't defined and was failing to build because of it. Also, it might be helpful to note that EASTL will build as a dynamic library if BUILD_SHARED_LIBS is set to true and will throw a link error because it can't find the EASTL.lib file. Somehow mine got set so I had to explicitly add STATIC to the add_library() line in EASTL's cmakelists.