Macro to put after your main() function.
In order to maintain cross-platform compatibility, you have to put this
macro at the very end of your main function. This macro uses some `magic'
to mangle your main procedure on platforms that need it like Windows,
some flavours of UNIX or MacOS X. On the other platforms this macro
compiles to nothing, so you don't have to #ifdef around it. Example:
/* more stuff goes here */