mn10300 relaxing bug

[DJ Delorie]

Fun question here: The mn10300 uses function symbols to keep track of
which relaxations are possible (i.e. it's a flags field in the symtab
hash).  However, when relaxing C++ thunks there are cases where you
have two symbols referring to the start of one function.  In this
case, sometimes one symbol indicates that the call->calls relaxation
can happen, but the other one says it can't.  So, the relaxation
happens and half the calls work and the other crash.

How are we supposed to deal with this?