The recent change to generate type functions for more types with
identity comparisons caused us to generate some unnecessary functions,
and even caused a compiler crash on Solaris due to phase ordering.
Avoid this by marking all generated and uncompared struct and array
types as incomparable, so that we don't try to generate type functions
for them.
Reviewed-on: https://go-review.googlesource.com/35110
From-SVN: r244327
