[ELF] - Fix relocation-group.test
[ELF] - Fix relocation-group.test

Main intention of test was to check that 
we do not crash, but for additional check
it previously run readobj for input object
instead of output.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@295161 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld