Wire the soname check into abicompat

Wire the soname check into abicompat

Now that the comparison engine knows how to take SONAMEs into account
during ABI abi comparison, it's feasible to make abicompat leverage
that capability.  This patch does just that.

	* include/abg-comparison.h (corpus_diff::soname_changed): Declare
	new member function.
	* src/abg-comparison.cc (corpus_diff::soname_changed): Define new
	member function.
	(corpus_diff::length): Use the new corpus_diff::soname_changed()
	method.
	* tests/data/test-abicompat/libtest4-soname-changed-v0.so: New
	test input data.
	* tests/data/test-abicompat/libtest4-soname-changed-v1.so:
	Likewise.
	* tests/data/test-abicompat/test4-soname-changed-app: Likewise.
	* tests/data/test-abicompat/test4-soname-changed-report-0.txt:
	Likewise.
	* tests/data/test-abicompat/test4-soname-changed-app.cc: Source
	code for one of the binaries above.
	* tests/data/test-abicompat/test4-soname-changed-v0.cc: Likewise.
	* tests/data/test-abicompat/test4-soname-changed-v1.cc: Likewise.
	* tests/test-abicompat.cc (in_out_specs): Add the new test input
	data to the list of input data to run this harness over.
	(main): Take the soname change in account to determine if the
	change is ABI incompatible.
	* tests/data/Makefile.am: Add the new test input data above to source
	distribution.

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