mono/referencesource — pull request #2 by esdrubal (2014-12-02 17:38:53+00:00)
Title: [System.Core] ReaderWriterLockSlim.cs now builds with mono.

* Adds support to build without Code Access Security, by using the
define DISABLE_CAS_USE.

* Builds without [MethodImpl(MethodImplOptions.AggressiveInlining)]
when target framework version is lower than 4.5.

* Use Thread.Volatile instead of Volatile.Read when target framework
version is lower than 4.5.