cranelift: Remove of/nof overflow flags from icmp (#4879)

* cranelift: Remove of/nof overflow flags from icmp

Neither Wasmtime nor cg-clif use these flags under any circumstances.
From discussion on #3060 I see it's long been unclear what purpose these
flags served.

Fixes #3060, fixes #4406, and fixes #4875... by deleting all the code
that could have been buggy.

This changes the cranelift-fuzzgen input format by removing some IntCC
options, so I've gone ahead and enabled I128 icmp tests at the same
time. Since only the of/nof cases were failing before, I expect these to
work.

* Restore trapif tests

It's still useful to validate that iadd_ifcout's iflags result can be
forwarded correctly to trapif, and for that purpose it doesn't really
matter what condition code is checked.

cranelift/codegen/meta/src/shared/instructions.rs

@@ -1759,12 +1759,6 @@ pub(crate) fn define(
         | sge    | uge      | Greater than or equal |
         | sgt    | ugt      | Greater than          |
         | sle    | ule      | Less than or equal    |
-        | of     | *        | Overflow              |
-        | nof    | *        | No Overflow           |
-
-        \* The unsigned version of overflow condition for add has ISA-specific semantics and thus
-        has been kept as a method on the TargetIsa trait as
-        [unsigned_add_overflow_condition][crate::isa::TargetIsa::unsigned_add_overflow_condition].
 
         When this instruction compares integer vectors, it returns a boolean
         vector of lane-wise comparisons.