[PATCH] Fix path::iterator post-increment and post-decrement

[Jonathan Wakely <jwakely at redhat dot com>]

I made a dumb mistake in the post-inc and post-dec operators for
the path::iterator type, forgetting that _M_cur is sometimes null (for
a single-element path).

	* include/experimental/bits/fs_path.h (path::iterator++(int))
	(path::iterator--(int)): Fix for paths with only one component.
	* testsuite/experimental/filesystem/path/itr/traversal.cc: Test
	post-increment and post-decrement.

Tested powerpc64le-linux, committed to trunk.

It's too late to fix this on the gcc-5 branch but I'll backport it to
gcc-6 and gcc-7 soon.

Attachment: patch.txt
Description: Text document