To fix this warning:
../src/cairo-malloc-private.h:83:32: warning: comparison is always false due to limited range of data type [-Wtype-limits]
83 | ((size) != 0 && (size_t) (a) >= SIZE_MAX / (size_t) (size) ? NULL : \
| ^~
Create two new macros to do the overflow checks:
_cairo_addl_size_t_overflow and _cairo_mul_size_t_overflow. Implement
them using compiler builtins where available.
Update cairo-malloc-private to use these fuctions and add an overflow
test to test the functions.
