* src/abg-ir.cc (namespace_decl::~namespace_decl): Add this
missing virtual constructor definition.
* src/abg-reader.cc (read_context::{get_cur_decl,pop_decl}):
Return a null pointer when the decls stack is empty.
(update_read_context): Don't try to de-reference a NULL cur_decl.
(read_input): Don't try to poke at file validity here. What was I
thinking. Really test for advance_cursor to return 1, expressing
success.
* src/abg-reader.h (read_file): Fix style.
* Makefile.am: Add tests sub-directory.
* configure.ac: Build with debugging-friendly options if the
ABIGAIL_DEBUG env variable is set. Generate tests/Makefile.
* tests/Makefile.am: New file.
* tests/test-read-write.cc: Likewise.
* tests/test-utils.{h,cc}: Likewise.
* tests/data/test-read-write/input0.xml: Likewise.
