python: Add qualified parameter to gdb.Breakpoint

python: Add qualified parameter to gdb.Breakpoint

This patch adds the possibility to pass a qualified=True|False parameter
when creating a breakpoint in Python.  It is equivalent to using
-qualified in a linespec.  The parameter actually accepts any Python
value, and converts it to boolean using Python's standard rules for
that (https://docs.python.org/3/library/stdtypes.html#truth).

Unlike the -source/-line/-function/-label parameters, it is possible to
use -qualified with a "normal" (non-explicit) linespec.  Therefore, it
is possible (unlike these other parameters) to use this new parameter
along with the spec parameter.

I updated the py-breakpoint.exp test.  To be able to test multiple
locations using a namespace, I had to switch the test case to compile as
C++.  If we really wanted to, we could run it as both C and C++, but
omit the C++-specific parts when running it as C.

gdb/ChangeLog:

	* location.h (string_to_event_location): Add match_type
	parameter.
	* location.c (string_to_event_location): Likewise.
	* python/py-breakpoint.c (bppy_init): Handle qualified
	parameter.

gdb/doc/ChangeLog:

	* python.texi (Manipulating breakpoints using Python): Document
	qualified parameter to gdb.Breakpoint.

gdb/testsuite/ChangeLog:

	* gdb.python/py-breakpoint.c (foo_ns::multiply): New function.
	* gdb.python/py-breakpoint.exp: Compile the test case as c++,
	call test_bkpt_qualified.
	(test_bkpt_qualified): New proc.