python: Create Python bindings for record history.

This patch adds three new functions to the gdb module in Python:
	- start_recording
	- stop_recording
	- current_recording
start_recording and current_recording return an object of the new type
gdb.Record, which can be used to access the recorded data.

Signed-off-by: Tim Wiederhake <tim.wiederhake@intel.com>

gdb/ChangeLog

	* Makefile.in (SUBDIR_PYTHON_OBS): Add python/py-record.o.
	(SUBDIR_PYTHON_SRCS): Add python/py-record.c.
	* python/py-record.c: New file.
	* python/python-internal.h (gdbpy_start_recording,
	gdbpy_current_recording, gdpy_stop_recording,
	gdbpy_initialize_record): New export.
	* python/python.c (_initialize_python): Add gdbpy_initialize_record.
	(python_GdbMethods): Add gdbpy_start_recording,
	gdbpy_current_recording and gdbpy_stop_recording.

Change-Id: I772aa9aa068621443f10a330b11dc7dc9a63face