Make any_cast compare typeinfo as well as function pointers

It's possible for the function pointer comparison to fail even though
the type is correct, because the function could be defined multiple
times with different addresses when shared libraries are in use.

Retain the function pointer check for the common case where the check
succeeds, but compare typeinfo (if RTTI is enabled) if the first check
fails.

	* include/experimental/any (__any_caster): Use RTTI if comparing
	addresses fails, to support non-unique addresses in shared libraries.
	* include/std/any (__any_caster): Likewise.

From-SVN: r271557