[msan] Fix linkage type of __msan_track_origins.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@173157 91177308-0d34-0410-b5e6-96231b3b80d8
[msan] Follow -msan-keep-going in reports from interceptors.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@173158 91177308-0d34-0410-b5e6-96231b3b80d8