CTI_MAX multiply defined?

[Gary Funck]

revision 1.18 of optabs.h (date: 2003/10/07) introduced a
new enumerated type, convert_optab_index, which declares
a value for CTI_MAX.  However, c-common.h also declares
CTI_MAX as the largest value for c_tree_index, and this
declaration pre-dates the optabs.h change. I ran into it
while working on some changes that I was porting forward
to 3.4.3. If including both optabs.h and c-common.h is
permitted, then it looks as if the optabs.h definition
needs to change.