Fix returning error message in LLVMLinkModules

On error, the temporary output stream wouldn't be flushed and therefore the
caller would see an empty error message.

Patch by Antoine Pitrou

Differential Revision: http://reviews.llvm.org/D10241 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239646 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed