* Added additional code to remove the conv instruction present in the initialization part of the pinned region.
* Extended the code responsible for removing the unpin stloc to correctly match the inverted condition found in MCS 2.6.4 compiled code.
* Enabled already present correctness test to run for MCS 2.6.4.
This is a more generalized version of the fix on PR #3110 proposed by @ElektroKill.