handle conflict between DR and executable in earliest injection

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on November 25, 2011 12:15:02_

for earliest injection ( issue #234 ), for now I'm assuming we don't need to
rebase. only ntdll and executable in process but it's possible executable
could conflict.

should at least check for conflict and if so could fall back to late
injection? though not trivial to locate executable in child.

long-term: rebase from parent, or rebase in child via bootstrap routine
that somehow has no relocs in itself?

_Original issue: http://code.google.com/p/dynamorio/issues/detail?id=625_