Mostly rewrite debug info generation in terms of llvm/Analysis/DebugInfo.h. Add getCompilationModule to Dsymbol and fix template compile unit decision code. Runtime compiles with -g again.

module tangotests.lazy1;

extern(C) int printf(char*, ...);

void main()
{
    lazystr("whee\n");
}

void lazystr(lazy char[] msg)
{
    printf("%.*s", msg.length, msg.ptr);
}