ExecutionEngine: make COFF Thumb2 assertions non-tautological

The overflow detection assertions were tautological due to truncation.
Adjust them to no longer be tautological.

Patch by Alex Langford!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316303 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed