gas dw2gencfi memory leaks

gas dw2gencfi memory leaks

Some of these could have remained as malloc'd memory, but that would
require quite a bit of code to traverse frch_cfi_data for example, and
would rely on matching cfi directives (ie. valid input).  Just put
them on the notes obstack instead.

	* dw2gencfi.c (alloc_fde_entry): Use notes_calloc.
	(alloc_cfi_insn_data): Likewise.
	(cfi_end_fde): Don't free frch_cfi_data.
	(cfi_add_label): Use notes_strdup.
	(cfi_add_CFA_remember_state): Use notes_alloc.
	(cfi_add_CFA_restore_state): Don't free.
	(dot_cfi_escape): Use notes_alloc.
	(cfi_finish): Free cies after each pass, not before.  Clear
	out static vars too.