Update of the release notes: '-z' is also forwarded to the linker

git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_35@215313 91177308-0d34-0410-b5e6-96231b3b80d8
Also describe the new check 'alpha.core.TestAfterDivZero'

git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_35@215314 91177308-0d34-0410-b5e6-96231b3b80d8