[Bug libgcc/87189] libgcc/gthr-posix.h (__gthread_active_p) makes unwarranted assumptions about libpthread.a

[ppluzhnikov at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87189

--- Comment #1 from Paul Pluzhnikov <ppluzhnikov at google dot com> ---
Crash stack for reference:

Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x0000000000477f7c in __gthread_mutex_lock (__mutex=0x6a7380
<object_mutex>) at ./gthr-default.h:748
#2  __register_frame_info_bases (begin=<optimized out>, ob=0x6a2300 <object>,
tbase=<optimized out>, dbase=<optimized out>) at
../../../libgcc/unwind-dw2-fde.c:103
#3  0x0000000000400acd in frame_dummy ()
#4  0x0000000000000001 in ?? ()
#5  0x000000000040194c in __libc_csu_init (argc=-9472, argc@entry=1,
argv=argv@entry=0x7fffffffdc78, envp=0x7fffffffdc88) at elf-init.c:88
#6  0x0000000000401170 in __libc_start_main (main=0x400add <main>, argc=1,
argv=0x7fffffffdc78, init=0x4018d0 <__libc_csu_init>, fini=0x401970
<__libc_csu_fini>, rtld_fini=0x0, stack_end=0x7fffffffdc68) at
../csu/libc-start.c:264
#7  0x00000000004009fa in _start () at ../sysdeps/x86_64/start.S:120