Support: add additional comment for ARM EH structure

Replicate the fact that ARM::WinEH::RuntimeFunction purposefully does not merge
functions to accommodate raw data access use cases in tools such as readobj.
Pointed out by Renato during post-commit review.

No functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210189 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed