Included the TestVirtualFunctionRetVal for Linux (#846)
Included the TestVirtualFunctionRetVal for Linux (#846)

Fixes #755

It turns out this wasn't a bug in our code because the test passes now with no changes whatsoever. My only guess is that there used to be a bug in Mono.
inordertotest/CppSharp,u255436/CppSharp,ktopouzi/CppSharp,inordertotest/CppSharp,zillemarco/CppSharp,mohtamohit/CppSharp,ktopouzi/CppSharp,mohtamohit/CppSharp,ddobrev/CppSharp,mono/CppSharp,mono/CppSharp,mono/CppSharp,ddobrev/CppSharp,inordertotest/CppSharp,mono/CppSharp,u255436/CppSharp,ktopouzi/CppSharp,mono/CppSharp,u255436/CppSharp,mohtamohit/CppSharp,ktopouzi/CppSharp,inordertotest/CppSharp,mono/CppSharp,u255436/CppSharp,inordertotest/CppSharp,u255436/CppSharp,ddobrev/CppSharp,ktopouzi/CppSharp,mohtamohit/CppSharp,zillemarco/CppSharp,zillemarco/CppSharp,zillemarco/CppSharp,mohtamohit/CppSharp,ddobrev/CppSharp,zillemarco/CppSharp,ddobrev/CppSharp