[llvm-isel-fuzzer] Use "--" as separator rather than '='.

Summary: OSS-Fuzz doesn't support '=' in filenames.

Reviewers: bogner, kcc

Reviewed By: kcc

Subscribers: javed.absar, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D38866

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315647 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed