gas macro memory leaks

gas macro memory leaks

This tidies memory allocated for entries in macro_hash.  Freeing the
macro name requires a little restructuring of the define_macro
interface due to the name being used in the error message, and exposed
the fact that the name and other fields were not initialised by the
iq2000 backend.

There is also a fix for
 .macro .macro
 .endm
 .macro .macro
 .endm
which prior to this patch reported
mac.s:1: Warning: attempt to redefine pseudo-op `.macro' ignored
mac.s:3: Error: Macro `.macro' was already defined
rather than reporting the attempt to redefine twice.

	* macro.c (macro_del_f): New function.
	(macro_init): Use it when creating macro_hash.
	(free_macro): Free macro name too.
	(define_macro): Return the macro_entry, remove idx, file, line and
	namep params.  Call as_where.  Report errors here.  Delete macro
	from macro_hash on attempt to redefined pseudo-op.
	(delete_macro): Don't call free_macro.
	* macro.h (define_macro): Update prototype.
	* read.c (s_macro): Adjust to suit.
	* config/tc-iq2000.c (iq2000_add_macro): Init all fields of
	macro_entry.