New attribute 'last' for gdb.Symtab_and_line.
* NEWS (Python Scripting): Add entry about the new attribute.
* python/py-symtab.c (salpy_get_last): New function which
implements the get method for the 'last' attribute of
gdb.Symtab_and_line.
(sal_object_getset): Add entry for the 'last' attribute.
doc/
* gdb.texinfo (Symbol Tables In Python): Add description about
the new 'last' attribute of gdb.Symtab_and line.
testsuite/
* gdb.python/py-symtab.exp: Add tests to test the new attribute
'last' of gdb.Symtab_and_line.
* gdb.python/py-symbol.c: Move break point comment to enable
testing of gdb.Symtab_and_line.last.