GCC5 compat: we cannot use inherited constructor, because it doesn't implement backport of P0136

Add post_call(epilogue) handler before `Return` of the origin function, as implementation is replace the origin `Return Address` of the function.

Add pre_call(prologue) handler before running the origin function,

Store the streambuf from cerr up-front because cout may get redirected when running tests

Note that we do a copy+move to avoid having to SFINAE this constructor (and also avoid some perfect forwarding failure cases)

Store the streambuf from cout up-front because cout may get redirected when running tests