gdb/guile: allow for catchpoint type breakpoints in guile

gdb/guile: allow for catchpoint type breakpoints in guile

This commit adds initial support for catchpoints to the guile
breakpoint API.

This commit adds a BP_CATCHPOINT constant which corresponds to
GDB's internal bp_catchpoint.  The new constant is documented in the
manual.

The user can't create breakpoints with type BP_CATCHPOINT after this
commit, but breakpoints that already exist, obtained with
the (breakpoints) function, can now have this type.

gdb/ChangeLog:

	* guile/scm-breakpoint.c (bpscm_type_to_string): Handle
	bp_catchpoint.
	(bpscm_want_scm_wrapper_p): Likewise.
	(gdbscm_make_breakpoint): Likewise.
	(breakpoint_integer_constants): Likewise.

gdb/doc/ChangeLog:

	* guile.texinfo (Breakpoints In Guile): Add BP_CATCHPOINT
	description.

gdb/testsuite/ChangeLog:

	* gdb.guile/scm-breakpoint.exp (test_catchpoints): New proc.