Clean up abort.

* A dlmalloc usage error shouldn't call abort(3) because we want to
  cause a SIGSEGV by writing the address dlmalloc didn't like to an
  address the kernel won't like, so that debuggerd will dump the
  memory around the address that upset dlmalloc.

* Switch to the simpler FreeBSD/NetBSD style of registering stdio
  cleanup. Hopefully this will let us simplify more of the stdio
  implementation.

* Clear the stdio cleanup handler before we abort because of a dlmalloc
  corruption error. This fixes the reported bug, where we'd hang inside
  dlmalloc because the stdio cleanup reentered dlmalloc.

Bug: 9301265
Change-Id: Ief31b389455d6876e5a68f0f5429567d37277dbc
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 664cec1..e3a40bc 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -58,7 +58,10 @@
 int	__sflags(const char *, int *);
 int	__vfprintf(FILE *, const char *, __va_list);
 
-extern void __atexit_register_cleanup(void (*)(void));
+/*
+ * Function to clean up streams, called from abort() and exit().
+ */
+extern void (*__cleanup)(void);
 extern int __sdidinit;
 
 /*