Conditionalise inclusion of link.h on !SANITIZER_ANDROID.

Hopefully fixes the Android build.

Differential Revision: http://llvm-reviews.chandlerc.com/D1551

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@189696 91177308-0d34-0410-b5e6-96231b3b80d8