Object/COFF: Fix off-by-one error for object having lots of relocations

llvm-objdump printed out an error message for this off-by-one error,
but because it always exits with 0 whether or not it found an error,
the test (llvm-objdump/coff-many-relocs.test) succeeded.
I made llvm-objdump exit with EXIT_FAILURE when an error is found.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222852 91177308-0d34-0410-b5e6-96231b3b80d8