Cleanup complex datatypes and update datatypes and operator code to use C99.

This commit changes the underlying opal complex datatypes to match the
C99 types: float _Complex, double _Complex, and long double _Complex. The
fortran and C++ types now are aliases to these basic types instead of
structure types. The operators in ompi/mca/op/base now work on only the
C99 types and the fortran types use these operators if the fortran type
matches a C complex type (this should almost always be the case.)

C99 is not is use in both the datatype and operator code and should make
the code both cleaner and much less fragile.