[BUG-FIX][XCOFF] fixed a bug of XCOFFObjectFile.cpp when there is padding at...

[BUG-FIX][XCOFF] fixed a bug of XCOFFObjectFile.cpp when there is padding at the last csect of a sections

SUMMARY:
  Fixed a bug of XCOFFObjectFile.cpp when there is padding at the last csect of a sections.
when there is a tail padding of a section, but the value of CurrentAddressLocation do not be increased by the padding size. it will hit assert assert(CurrentAddressLocation == Section->Address && "We should have no padding between sections.");

Reviewers: daltenty,hubert.reinterpretcast,

Differential Revision: https://reviews.llvm.org/D70859