[TRE] Simplify canTRE() a bit using all_of(). NFCI.

This has a ~11 years old FIXME, which may not be true today.
We might consider removing this code altogether.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308319 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed