Handle stepping through a trampoline where the jump target is calculated a...

Handle stepping through a trampoline where the jump target is calculated a runtime - and so doesn't match
the name of the PLT entry.  This solution assumes a naming convention agreed upon by us and the system folks,
and isn't general.  The general solution requires actually finding & calling the resolver function if it
hasn't been called yet.  That's more tricky.

llvm-svn: 144981