New probe type: DTrace USDT probes.

New probe type: DTrace USDT probes.

This patch adds a new type of probe to GDB: the DTrace USDT probes.  The new
type is added by providing functions implementing all the entries of the
`probe_ops' structure defined in `probe.h'.  The implementation is
self-contained and does not depend on DTrace source code in any way.

gdb/ChangeLog:

2015-02-7  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* breakpoint.c (BREAK_ARGS_HELP): Help string updated to mention
	the -probe-dtrace new vpossible value for PROBE_MODIFIER.
	* configure.ac (CONFIG_OBS): dtrace-probe.o added if BFD can
	handle ELF files.
	* Makefile.in (SFILES): dtrace-probe.c added.
	* configure: Regenerate.
	* dtrace-probe.c: New file.
	(SHT_SUNW_dof): New constant.
	(dtrace_probe_type): New enum.
	(dtrace_probe_arg): New struct.
	(dtrace_probe_arg_s): New typedef.
	(struct dtrace_probe_enabler): New struct.
	(dtrace_probe_enabler_s): New typedef.
	(dtrace_probe): New struct.
	(dtrace_probe_is_linespec): New function.
	(dtrace_dof_sect_type): New enum.
	(dtrace_dof_dofh_ident): Likewise.
	(dtrace_dof_encoding): Likewise.
	(DTRACE_DOF_ENCODE_LSB): Likewise.
	(DTRACE_DOF_ENCODE_MSB): Likewise.
	(dtrace_dof_hdr): New struct.
	(dtrace_dof_sect): Likewise.
	(dtrace_dof_provider): Likewise.
	(dtrace_dof_probe): Likewise.
	(DOF_UINT): New macro.
	(DTRACE_DOF_PTR): Likewise.
	(DTRACE_DOF_SECT): Likewise.
	(dtrace_process_dof_probe): New function.
	(dtrace_process_dof): Likewise.
	(dtrace_build_arg_exprs): Likewise.
	(dtrace_get_arg): Likewise.
	(dtrace_get_probes): Likewise.
	(dtrace_get_probe_argument_count): Likewise.
	(dtrace_can_evaluate_probe_arguments): Likewise.
	(dtrace_evaluate_probe_argument): Likewise.
	(dtrace_compile_to_ax): Likewise.
	(dtrace_probe_destroy): Likewise.
	(dtrace_gen_info_probes_table_header): Likewise.
	(dtrace_gen_info_probes_table_values): Likewise.
	(dtrace_probe_is_enabled): Likewise.
	(dtrace_probe_ops): New variable.
	(info_probes_dtrace_command): New function.
	(_initialize_dtrace_probe): Likewise.
	(dtrace_type_name): Likewise.