--cuda-host-only should not disable linking phase.

Host-only cuda compilation does produce valid host object
file and in some cases users do want to proceed on to the linking phase.
The change removes special case that stopped compilation pipeline at
the Assembly phase. Device-side compilation is still stopped early
by the types::getCompilationPhases().

Differential Revision: http://reviews.llvm.org/D11573

llvm-svn: 243478