[svn r374] Move label target basic block from AST to IRFunction. This is a first step to allowing labels to be emitted multiple times. (for instance within finally blocks)

module scope1;
extern(C) int printf(char*, ...);
void main()
{
    printf("1\n");
    {
        scope(exit) printf("2\n");
    }
    printf("3\n");
}