[Sanitizer] State that sanitizer_libc.h header can be included in the user code (and therefore it shouldn't include other sanitizer runtime headers).
[Sanitizer] State that sanitizer_libc.h header can be included in the user code (and therefore it shouldn't include other sanitizer runtime headers).

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@158707 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt