Supported from GCC 8 and up, and Compiler Explorer suggests it works as
expected with Clang since 3.6 (2014).
- Fixes situation where building embedded MicroPython with -O0 and
MICROPY_NLR_X64 crashes at runtime (due to nlr_push pushing the
frame pointer register EBP). Closes#12421.
- Allows removing the macOS tweak to undo pushing EBP onto the stack
in the generated function prelude.
Signed-off-by: Angus Gratton <angus@redyak.com.au>