Modify InputSectionBase::getLocation to add section and offset to every loc.

The section and offset can be very helpful in diagnosing certian errors.
For example on a relocation overflow or misalignment diagnostic:

test.c:(function  foo): relocation R_PPC64_ADDR16_DS out of range: ...

The function foo can have many R_PPC64_ADDR16_DS relocations. Adding the offset
and section will identify exactly which relocation is causing the failure.

Differential Revision: https://reviews.llvm.org/D56453

llvm-svn: 350828