[PECOFF] Sort SEH table entries according to its value.

It looks like the contents of the table need to be sorted according to its
value, so that the runtime can find the entry by binary search. I'm not 100%
sure if we really have to do that, but at least I can say it's safe to do
because the contents of .sxdata is just a list of exception handlers' RVAs.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@202550 91177308-0d34-0410-b5e6-96231b3b80d8