libstdc++: Use 'inline' consistently in std::exception_ptr [PR 97729]

libstdc++: Use 'inline' consistently in std::exception_ptr [PR 97729]

With PR c++/67453 fixed we can rely on the 'used' attribute to emit
inline constructors and destructors in libsupc++/eh_ptr.cc. This means
we don't need to suppress the 'inline' keyword on them in that file, and
don't need to force 'always_inline' on them in other files.

libstdc++-v3/ChangeLog:

	PR libstdc++/97729
	* libsupc++/exception_ptr.h (exception_ptr::exception_ptr())
	(exception_ptr::exception_ptr(const exception_ptr&))
	(exception_ptr::~exception_ptr()): Remove 'always_inline'
	attributes. Use 'inline' unconditionally.