Explicit locations: MI support for explicit locations

Explicit locations: MI support for explicit locations

This patch adds support for explicit locations to MI's -break-insert
command. The new options, documented in the User Manual, are
--source, --line, --function, and --label.

gdb/ChangeLog:

	* mi/mi-cmd-break.c (mi_cmd_break_insert_1): Add support for
	explicit locations, options "--source", "--function",
	"--label", and "--line".

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-break.exp (test_explicit_breakpoints): New proc.
	(at toplevel): Call test_explicit_breakpoints.
	* gdb.mi/mi-dprintf.exp: Add tests for explicit dprintf
	breakpoints.
	* lib/mi-support.exp (mi_make_breakpoint): Add support for
	breakpoint conditions, "-cond".