C89 , C99 or C++ output mode

[thradams]

Code generated for C or C++ can be different:

For instance cast to (void*) on free, and cast from (void*) in malloc.
Some C programmers can find these casts annoying, and others may want to generated code to be compiled in C++.

The same for compound literals and designed initializers.

[thradams]

Undefined for now.
C99 only