[Objective-c] Stop attaching section "datacoal_nt" to global variables.

The current macho linker just copies symbols in section datacoal_nt to
section data, so it doesn't really matter whether or not section
"datacoal_nt" is attached to the global variable.

This is a follow-up to r250370, which made changes in llvm to stop
putting functions and data in the *coal* sections.

rdar://problem/24528611

llvm-svn: 260496