Not running in C++

Hi,

the ert_main.cpp is producing an error under linux when you try to build you model with C++. 
Due to a return statement with no value under 2019b.
The exact message is: 

ert_main.cpp:146:9: error: return-statement with no value, in function returning ‘void*’ [-fpermissive]

Same for the tmf file there you need to filter out rt_main.cpp aswell.

cheers.
