4050 – [CTFE] array struct member slice update

(Not tested with the latest bug fixes, so this can be already fixed)
struct Foo {
 int[1] data;
}
int bar() {
 Foo f;
 f.data = [1];
 return 0;
}
enum int _ = bar();
void main() {}
dmd 2.042 gives:
test.d(6): Error: Slice operation f.data[] = [1] cannot be evaluated at compile time
test.d(9): Error: cannot evaluate bar() at compile time
test.d(9): Error: cannot evaluate bar() at compile time

Fixed.
D1:
https://github.com/D-Programming-Language/dmd/commit/ef2a0f1da10331c4de102ca3e029ea1c1c1a46bf
D2:
https://github.com/D-Programming-Language/dmd/commit/0219a5f0dcc88076759a4c472582954d0fb804b0