[CMake] Provide direct support for building sanitized runtimes
[CMake] Provide direct support for building sanitized runtimes

This avoids having to rely on magic separators and special parsing.

Differential Revision: https://reviews.llvm.org/D48061

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@335704 91177308-0d34-0410-b5e6-96231b3b80d8

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