Add liblog to ubsan `UBSAN_DYNAMIC_LIBS`

Summary: liblog is still required to create ubsan runtimes on Android when __ANDROID_API__ < 21.

Reviewers: eugenis, vsk

Subscribers: kubamracek, mgorny, pirama, srhines, llvm-commits

Differential Revision: https://reviews.llvm.org/D35915

llvm-svn: 309180