Add two new methods global_block and static_block to gdb.Symtab
objects.
* NEWS (Python scripting): Add entry about the new methods.
* python/py-symtab.c (stpy_global_block): New function which
implements the gdb.Symtab.global_block() method.
(stpy_static_block): New function which implements the
gdb.Symtab.static_block() method.
(symtab_object_methods): Add entries for the two new methods.
* testsuite/gdb.python/py-symbol.exp: Add tests to test the new
methods gdb.Symtab.global_block() and gdb.Symtab.static_block().
* tessuite/gdb.python/py-symbol.c: Add new struct to help test
gdb.Symtab.static_block().
* doc/gdb.texinfo (Symbol Tables In Python): Add documentation
about the new methods global_block and static_block on
gdb.Symtab objects.
