[yaml2obj] - Do not skip zeroes blocks if there are relocations against them.

This is for -D -reloc combination.

With this patch, we do not skip the zero bytes that have a relocation against
them when -reloc is used. If -reloc is not used, then the behavior will be the same.

Differential revision: https://reviews.llvm.org/D58174

llvm-svn: 354319