* printcmd.c (printf_command): Add seen_big_h, seen_big_d and

	* printcmd.c (printf_command): Add seen_big_h, seen_big_d and
	seen_double_big_d, treat the new H, D, and DD modifiers as length
	modifiers.
	* doc/gdb.texinfo (Output): Update documentation on using printf with DFP
	types.
	* testsuite/gdb.base/printcmds.exp (test_printf_with_dfp): Update
	printf calls with required float modifiers.