Propagate private type diff category through refs/qualified type diffs

Propagate private type diff category through refs/qualified type diffs

This patch is the third of the series:

    Internal pretty repr of union cannot be flat representation
    Fix anonymous union constructed under the wrong context
    Propagate private type diff category through refs/qualified type diffs

The intent of this series is to fix the bug:

    https://sourceware.org/bugzilla/show_bug.cgi?id=24410
    "Empty change report emitted for libpoppler-qt5.so.1.18.0"

We (mistakenly) don't propagate private type diff categories through
reference and qualified type diffs.  This leads to some diff nodes not
being suppressed just because they are private type diffs which
category weren't properly propagated.

This patch fixes this.

Note that the tests updated in this patch reflect the regression tests
changes needed for the entire set of 3 patches.

	* src/abg-comparison.cc
	(suppression_categorization_visitor::visit_end): Propagate
	suppressed and private type diff categories for reference and
	qualified types.  For qualified types, make sure they don't have
	local changes.  Even when there are no local changes, do not
	propagate private diff categories to typedefs.
	* tests/data/test-annotate/test17-pr19027.so.abi: Adjust.
	* tests/data/test-annotate/test21-pr19092.so.abi: Likewise.
	* tests/data/test-read-dwarf/PR22122-libftdc.so.abi: Likewise.
	* tests/data/test-read-dwarf/test10-pr18818-gcc.so.abi: Likewise.
	* tests/data/test-read-dwarf/test11-pr18828.so.abi: Likewise.
	* tests/data/test-read-dwarf/test12-pr18844.so.abi: Likewise.
	* tests/data/test-read-dwarf/test16-pr18904.so.abi: Likewise.
	* tests/data/test-read-dwarf/test17-pr19027.so.abi: Likewise.
	* tests/data/test-read-dwarf/test21-pr19092.so.abi: Likewise.
	* tests/data/test-read-dwarf/test22-pr19097-libstdc++.so.6.0.17.so.abi: Likewise.
	* tests/data/test-read-dwarf/test9-pr18818-clang.so.abi: Likewise.

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