Drop examples/rtc_common.hpp, use cuda::rtc::render to print compilation options

[eyalroz]

The examples/rtc_common.hpp file only contains two functions, both regard printing compilation options. These are, in fact, unnecessary, since the wrappers offer cuda::rtc::render(), which gets us an std::string representation of the options. So, let's get rid of that code and its uses.

Note that this will remove the only use of cuda::rtc::marshalled_options_t in our example code.