re PR libstdc++/60612 (Throwing exception, catching and rethrowing (std::exception_ptr) in destructor leads to segfault)

	PR libstdc++/60612
	* libsupc++/eh_ptr.cc: Assert __cxa_dependent_exception layout is
	compatible with __cxa_exception.
	* libsupc++/unwind-cxx.h (__cxa_dependent_exception): Add padding.
	Fix typos in comments.
	* testsuite/18_support/exception_ptr/60612-terminate.cc: New.
	* testsuite/18_support/exception_ptr/60612-unexpected.cc: New.

From-SVN: r208871