incorrect substruct initialization

Bug exists in the latest ldc code. Here's a minimal test case:

struct Color {
    uint c;

}

struct Vertex {
    Color c;
}

void main() {
    Color c = {0xffffffff};

    auto v = Vertex(c);

    assert(v.c.c == 0xffffffff);  // fails in LDC
}

And here's the assembly generated after a plain compile:

08049590 <_Dmain>:
 8049590:       83 ec 2c                sub    $0x2c,%esp
 8049593:       c7 44 24 20 ff ff ff    movl   $0xffffffff,0x20(%esp)
 804959a:       ff 
 804959b:       c7 44 24 28 ff ff ff    movl   $0xffffffff,0x28(%esp)
 80495a2:       ff 
 80495a3:       8d 44 24 28             lea    0x28(%esp),%eax
 80495a7:       89 44 24 10             mov    %eax,0x10(%esp)
 80495ab:       89 44 24 18             mov    %eax,0x18(%esp)
 80495af:       83 f8 ff                cmp    $0xffffffff,%eax
 80495b2:       75 08                   jne    80495bc <_Dmain+0x2c>
 80495b4:       31 c0                   xor    %eax,%eax
 80495b6:       83 c4 2c                add    $0x2c,%esp
 80495b9:       c2 08 00                ret    $0x8
 80495bc:       8b 0d a4 1a 06 08       mov    0x8061aa4,%ecx
 80495c2:       89 4c 24 04             mov    %ecx,0x4(%esp)
 80495c6:       8b 0d a0 1a 06 08       mov    0x8061aa0,%ecx
 80495cc:       89 0c 24                mov    %ecx,(%esp)
 80495cf:       c7 44 24 08 0f 00 00    movl   $0xf,0x8(%esp)
 80495d6:       00 
 80495d7:       e8 24 00 00 00          call   8049600 <_d_assert>
 80495dc:       8d 74 26 00             lea    0x0(%esi,%eiz,1),%esi

Contrary to the commit message, this was not fixed in [913]. StructLiteralExp::toElem is wrong, the generated struct literal type is { { i32 }* } whereas the Vertex is { { i32 } }.

fixed in rev [915]