bug#21999: 25.0.50; Binary with --enable-checking immediately aborts with '0<=size'

[Eli Zaretskii]

> From: David Engster <deng@randomsample.de>
> Date: Mon, 23 Nov 2015 20:52:42 +0100
> 
> I've compiled from the emacs-25 branch (f146ea73a9ca6) with
> 
>   CFLAGS="-O0 -g3" ./configure --enable-checking
> 
> Running 'emacs -Q' directly from the src directory immediately aborts:
> 
>    lisp.h:1543: Emacs fatal error: assertion failed: 0 <= size
>    Fatal error 6: Aborted
> 
> Running 'emacs -nw -Q' runs fine, though.
> 
> gdb-Backtrace:
> 
> Breakpoint 1, terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at 
> emacs.c:371
> 371       signal (sig, SIG_DFL);
> (gdb) bt
> #0  terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:371
> #1  0x000000000060c908 in die (msg=0x7282e3 "0 <= size", file=0x728188 
> "lisp.h", line=1543) at alloc.c:7034
> #2  0x000000000057a983 in ASIZE (array=20941717) at lisp.h:1543

What kind of an object is 'array' in frame #2?  And what is the value
of 'size' in the same frame?

Dima, can you look into this?