[scudo] Remove duplicate cmake flags

Summary:
Now that common options are propagated again for runtimes build with D45507,
the -f{data,function}-sections flags are now duplicates, remove them.

Reviewers: alekseyshl

Reviewed By: alekseyshl

Subscribers: mgorny, delcypher, #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D45575

llvm-svn: 329925