MFC r335125-r335127, r335148, r335224

r335125:
libsa: cstyle cleanup for open/close/read/write sources

r335126:
libsa: f_rabuf could be NULL

It is possible that we will not get RA buffer from open(), therefore
we must validate RA.

r335127:
libsa: remobe unneeded check before free()

free() is checking for NULL, remove duplicate check.

r335148:
libsa: open() should use NULL instead of typecasted 0

r335224:
Remove empty directory