gdb/python: Add architecture method to gdb.PendingFrame

It could be useful to determine the architecture of a frame being
unwound during the frame unwind process, that is, before we have a
gdb.Frame, but when we only have a gdb.PendingFrame.

The PendingFrame already has a pointer to the gdbarch internally, this
commit just exposes an 'architecture' method to Python, and has this
return a gdb.Architecture object (list gdb.Frame.architecture does).

gdb/ChangeLog:

	* NEWS: Mention new Python API method.
	* python/py-unwind.c (pending_framepy_architecture): New function.
	(pending_frame_object_methods): Add architecture method.

gdb/testsuite/ChangeLog:

	* gdb.python/py-unwind.py (TestUnwinder::__call__): Add test for
	gdb.PendingFrame.architecture method.

gdb/doc/ChangeLog:

	* python.texi (Unwinding Frames in Python): Document
	PendingFrame.architecture method.

1 files changed, 3 insertions, 0 deletions

diff --git a/gdb/NEWS b/gdb/NEWS
index a116d62..29db073 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -117,6 +117,9 @@ GNU/Linux/RISC-V (gdbserver)	riscv*-*-linux*
   ** Commands written in Python can be in the "TUI" help class by
      registering with the new constant gdb.COMMAND_TUI.
 
+  ** New method gdb.PendingFrame.architecture () to retrieve the
+     architecture of the pending frame.
+
 *** Changes in GDB 9
 
 * 'thread-exited' event is now available in the annotations interface.