[yaml2obj] - Allow setting custom section types for implicit sections.

[yaml2obj] - Allow setting custom section types for implicit sections.

We were hardcoding the final section type for sections that
are usually implicit. The patch fixes that.

This also fixes a few issues in existent test cases and removes
one precompiled object.

Differential revision: https://reviews.llvm.org/D63267

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363377 91177308-0d34-0410-b5e6-96231b3b80d8