gold-plugin: Simplify naming of object files created with save-temps or obj-path.

Now we never append a number to the file name for task ID 0.

Differential Revision: https://reviews.llvm.org/D29160

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293132 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed