Fix a bug introduced by the move of AddressRanges.h into ADT.

The bug was introduced when the AddressRange class was no longer able to modify the End address directly and the entire range of the .text address range that contained the trailing empty symbol was replaced. There was no unit test for this, so it wasn't caught. I fixed the bug and added a unit test for it.

The effects of this bug are serious as the AddressOffsetSize in the header would be incorrectly calculated and an invalid GSYM would be created.

Differential Revision: https://reviews.llvm.org/D127811