[PECOFF] Sort x64 exception handler table.

Just like x86 exception handler table, the table for x64 needs to be sorted
so that runtime can binary search on it. Unlike x86, the table entry for x64
has multiple fields, and they need to be sorted according to its BeginAddress
field. This patch also fixes a bug in relocations.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@202874 91177308-0d34-0410-b5e6-96231b3b80d8