[compiler-rt] [Sanitizers] Extend ThreadDescriptorSize() for glibc-2.32-2.fc33.x86_64+i686

before:
  $ echo 'int main(){}'|clang -g -fsanitize=leak -x c++ -;./a.out
  Tracer caught signal 11: addr=0x7f4f73da5f40 pc=0x4222c8 sp=0x7f4f72cffd40
  ==1164171==LeakSanitizer has encountered a fatal error.
  ==1164171==HINT: For debugging, try setting environment variable LSAN_OPTIONS=verbosity=1:log_threads=1
  ==1164171==HINT: LeakSanitizer does not work under ptrace (strace, gdb, etc)
  $ _

after:
  $ echo 'int main(){}'|clang -g -fsanitize=leak -x c++ -;./a.out)
  $ _

I haven't verified the size cannot be affected by Fedora patches of
upstream glibc-2.32 - but I do not expect upstream glibc-2.32 would have
the last sizes `(1216, 2304)` from 2013 around glibc-2.12.

Differential Revision: https://reviews.llvm.org/D93386