Move definitions to the correct file.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@224190 91177308-0d34-0410-b5e6-96231b3b80d8
Make YAML files own MemoryBuffer.

YAML files have references such as StringRef to the underlying
MemoryBuffer, so we shouldn't deallocate the buffer.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@224191 91177308-0d34-0410-b5e6-96231b3b80d8