AOMP Release 0.6-2

This release uses the release_80 stable release of clang/llvm/lld/openmp repositories. The artifacts for this release include the patches to the release_80 repos to support openmp for amdgcn for release 0.6-2

Here are the fixes for 0.6-2

• Fixed issue with constant size teams and threads.
• Moved to the stable clang/llvm 8.0 code base
• Fixed code in deviceRTLs/amdgcn that set Max_Warp_Number to 16, was 64
• Enable Float16 for 0.6-2, disabled by default in release_80 merge
• Disable META data opt, and provide evar AMDGPU_ENABLE_META_OPT_BUG to enable
• Add archive handling for bc linking.
• For performance, rewrite select_outline_wrapper calls, to be direct calls.
  Example: change the generated from:
  @_HASHW_DeclareSharedMemory_cpp__omp_outlined___wrapper =
  local_unnamed_addr addrspace(4) constant i64 -4874776124079246075
  call void @select_outline_wrapper(i16 0, i32 %6, i64 -4874776124079246075)
  to:
  call void @DeclareSharedMemory_cpp__omp_outlined___wrapper(i16 0, i32 %6)
• In release_80, Loop_tripcount API is now used, so we need to limit num_groups/teams
  to no more than Max_Teams, fixes assertok_error, and snap4
  Also handle num_teams clause inside loop_tripcount logic.
• BALLOT_SYNC macro replaced with ACTIVEMASK in release_80