[Driver] Support object files in addition to static and shared libraries in compiler-rt

[Driver] Support object files in addition to static and shared libraries in compiler-rt

This change introduces support for object files in addition to static
and shared libraries which were already supported which requires
changing the type of the argument from boolean to an enum.

Differential Revision: https://reviews.llvm.org/D56044

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@355891 91177308-0d34-0410-b5e6-96231b3b80d8