Fix stencil clear

Some drivers (especially on Android) will obey the stencil test when clearing the stencil buffer (the specs says it shouldn't). This workaround ensure that the stencil buffer will properly be cleared.
Added missing semicolon
Merge pull request #2482 from prollin/patch-1

Fix stencil clear
Merge branch 'develop' of https://github.com/mono/MonoGame into InfiniteFlight