When e_shstrndx is broken, it is impossible to get a section name.
In this patch I improved the error message we show and
added tests for Object and for llvm-readelf/llvm-readobj
Message was changed in two places:
1) llvm-readelf/llvm-readobj previously used a code from Object/ELF.h,
now they have a modified version of it (it has less checks and allows
dumping broken things).
2) Code in Object/ELF.h is still used for generic cases.
Differential revision: https://reviews.llvm.org/D64714
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366203 91177308-0d34-0410-b5e6-96231b3b80d8