Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder

This will be used to consolidate the libgcc_s access for backtrace
and pthread_cancel.

Unlike the existing backtrace implementations, it provides some
hardening based on pointer mangling.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/misc/Versions b/misc/Versions
index 95666f6548..d5b348e83a 100644
--- a/misc/Versions
+++ b/misc/Versions
@@ -172,5 +172,6 @@ libc {
     __mmap; __munmap; __mprotect;
     __sched_get_priority_min; __sched_get_priority_max;
     __libc_allocate_once_slow;
+    __libc_unwind_link_get;
   }
 }