expand: EXTEND_BITINT CALL_EXPR results [PR114332]

The x86-64 and aarch64 psABIs (and the unwritten ia64 psABI part) say that
the padding bits of _BitInt are undefined, while the expansion internally
typically assumes that non-mode precision integers are sign/zero extended
and extends after operations.  We handle that mismatch with EXTEND_BITINT
done when reading from untrusted sources like function arguments, reading
_BitInt from memory etc. but otherwise keep relying on stuff being extended
internally (say in pseudos).
The return value of a function is an ABI boundary though too and we need
to extend that too.

2024-03-15  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/114332
	* expr.cc (expand_expr_real_1): EXTEND_BITINT also CALL_EXPR results.