* include/libabigail/abg-ir.h (struct ir_node_visitor, struct
traversable): New interfaces.
(translation_unit, scope_decl, type_decl, qualified_type_def)
(pointer_type_def, reference_type_def, enum_type_decl)
(typedef_decl, var_decl, function_decl, data_member)
(member_function, member_function_template)
(member_class_template): Implement the traversable interface,
overload the traversable::traverse pure virtual function.
* src/abg-ir.cc ({translation_unit, scope_decl, type_decl,
namespace_decl, qualified_type_def, pointer_type_def,
reference_type_def, enum_type_decl, typedef_decl, var_decl,
function_decl, class_decl::member_function, class_decl,
class_decl::data_member, class_decl::member_function_template,
class_decl::member_class_template, function_template_decl,
class_template_decl, }::traverse): Implement traversal.
(ir_node_visitor::visit): New method, overloaded for the types
above, which implement the traversable interface.
* tests/test-walker.cc: New test case program to showcase how to
use the new traversal API.
* tests/makefile.am: Add test-walker.cc to the build system.
* include/libabigail: New directory.
* include/Makefile.am: New file.
* include/libabigail/Makefile.am: New file.
* src/abg-*.h: Move these in include/libabigail/*.h
* src/Makefile.am: Set -I option to look for headers in include/libabigail
* doc/api/libabigail.doxy: Look for headers in include/libabigail
* tests/Makefile.am: Set -I option to look for headers in include/libabigail
* abigail.m4: Set includedir to $prefix/include/libabigail for
library used as a dep, or to srcdir/libabigail/include/libabigail
in GCC source tree.
* configure.ac: Add Makefile.am in include and include/libabigail
* abigail.m4: Look for headers in include/libabigail when the
libabigail is in in the source tree and in $incdir/libabigail when
it is installed as a dependency.
