[Dockerfiles] Use a newer version of ninja when building inside debian8.

Summary:
The debian8 repos have an old version of ninja that seems to sometimes crash
when building llvm.

Reviewers: ioeric, mehdi_amini

Reviewed By: ioeric

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D42304

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323134 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed