Add some alignment info where LLVM might otherwise be more pessimistic. In particular, %.nest_arg is always aligned even though it's bitcast from i8*. Pointers in vtables are also guaranteed to be stored at aligned addresses.

extern(C) int printf(char*, ...);
template Foo() { void test() { printf("test\n"); typeof(this).whee(); } }
class Bar { void whee() { printf("whee\n"); } mixin Foo!(); }
void main() { (new Bar).test(); }