bug#22263: Failed assertion (no good repro yet)

[Eli Zaretskii <eliz@gnu.org>]

> From: Clément Pit--Claudel <clement.pitclaudel@live.com>
> Date: Tue, 29 Dec 2015 17:53:28 +0100
> 
> I do not have a good repro for this yet, but I have been running into the following bug a few times a day in the last two days, after updating to the latest emacs-25; I didn't have this issue with a version from about a month ago:
> 
> > (gdb) run
> > Starting program: /build/emacs/src/emacs 
> > [Thread debugging using libthread_db enabled]
> > Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
> > [New Thread 0x7fffe9d0d700 (LWP 3717)]
> > [New Thread 0x7fffe3fff700 (LWP 3718)]
> > [New Thread 0x7fffe37fe700 (LWP 3719)]
> > lisp.h:1555: Emacs fatal error: assertion failed: 0 <= size
> > Fatal error 6: Aborted
> > lisp.h:1555: Emacs fatal error: assertion failed: 0 <= size
> > 
> > Program received signal SIGABRT, Aborted.
> > 0x00007ffff130920b in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:37
> > 37	../nptl/sysdeps/unix/sysv/linux/pt-raise.c: No such file or directory.
> > (gdb) backtrace
> > #0  0x00007ffff130920b in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:37
> > #1  0x0000000000588b41 in terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:398
> > #2  0x000000000061a40d in die (msg=0x73e9ab "0 <= size", file=0x73e850 "lisp.h", line=1555) at alloc.c:7036
> > #3  0x0000000000583b8e in ASIZE (array=14489661) at lisp.h:1555
> > #4  0x0000000000584aa6 in VECTORP (x=14489661) at lisp.h:2640
> > #5  0x0000000000677e4d in check_obarray (obarray=14489661) at lread.c:3723
> > #6  0x000000000067814f in intern_1 (str=0x74bf1a "auto-save-hook", len=14) at lread.c:3770
> > #7  0x0000000000585ae1 in intern (str=0x74bf1a "auto-save-hook") at lisp.h:3843
> > #8  0x00000000005e46f0 in Fdo_auto_save (no_message=44352, current_only=0) at fileio.c:5506
> > #9  0x000000000058af1c in shut_down_emacs (sig=6, stuff=0) at emacs.c:2030
> > #10 0x0000000000588af1 in terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:382
> > #11 0x000000000061a40d in die (msg=0x73e9ab "0 <= size", file=0x73e850 "lisp.h", line=1555) at alloc.c:7036
> > #12 0x0000000000583b8e in ASIZE (array=49306789) at lisp.h:1555
> > #13 0x0000000000584aa6 in VECTORP (x=49306789) at lisp.h:2640
> > #14 0x0000000000616b75 in compact_font_cache_entry (entry=18559459) at alloc.c:5349
> > #15 0x0000000000616ee0 in compact_font_caches () at alloc.c:5412

Fixed, thanks.