Description of problem:
Frama-c failed to parse its own stdio.h file

Version-Release number of selected component (if applicable):
frama-c-20.0-3.fc32.x86_64

How reproducible:
Always

Steps to Reproduce:
1. cat hello.c
#include <stdio.h>
  
int main(void)
{
  return 0;
}
2. frama-c hello.c -kernel-msg-key pp

Actual results:
[kernel:pp] 
  preprocessing with "gcc -E -C -I.  -I/usr/share/frama-c/libc -D__FRAMAC__ -D__FC_MACHDEP_X86_32 -dD -nostdinc -m32 hello.c"
[kernel] Parsing hello.c (with preprocessing)
[kernel:annot-error] FRAMAC_SHARE/libc/__fc_string_axiomatic.h:40: Warning: 
  unexpected token '\U00002124'
[kernel] User Error: warning annot-error treated as fatal error.
[kernel] User Error: stopping on file "hello.c" that has errors.
[kernel] Frama-C aborted: invalid user input.

Expected results:
No error

Additional info:
It may be related to gcc 10.1