[DynInst_API:] [dyninst/dyninst] b3504b: Fix catch block parsing (#1030)

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  Branch: refs/heads/master
  Home:   https://github.com/dyninst/dyninst
  Commit: b3504b61a6e1abcbcf74542e9bcb209437b78f21
      https://github.com/dyninst/dyninst/commit/b3504b61a6e1abcbcf74542e9bcb209437b78f21
  Author: Xiaozhu Meng <mxz297@xxxxxxxxx>
  Date:   2021-05-14 (Fri, 14 May 2021)

  Changed paths:
    M symtabAPI/src/Object-elf.C

  Log Message:
  -----------
  Fix catch block parsing (#1030)

The start address of a catch block is specified with a 2, 4, or 8 byte value.
SymtabAPI uses a 8-byte integer and properly clip the value when reading it.
However, there is an add to the read value, which will cause the final result
to wrap around under its specified size (such as 4-byte), but not under 8-byte.