Bug 18791 - libabigail fails to read the output of abidw

Bug 18791 - libabigail fails to read the output of abidw

The reader fails to set the access specifier for a member type.  Fixed
thus.

	* src/abg-reader.cc (read_context::get_scope_for_node): Take an
	access_specifier output parameter to set the access specifier of
	the current node in its scope.  Update the function to set the
	access_specifier.
	(read_context::build_or_get_type_decl): Adjust to set the access
	specifier of the type we are building, in case it's a member type.
	* tests/data/test-abidiff/test-PR18791-v{0,1}.so.abi: New test input files.
	* tests/data/test-abidiff/test-PR18791-report0.txt: New test
	output reference.
	* tests/data/Makefile.am: Add the new test material to the source
	distribution.
	* tests/test-abidiff.cc (specs): Add the new test inputs to the set of
	input files this test harness has to run over.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>