VertexArray Object implementation

Added VertexArray.cpp with a few
trivial function implementations.

Change-Id: I9ea0bf47b2c6a1f76392c5fc84837f1778946855
Reviewed-on: https://swiftshader-review.googlesource.com/2984
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>

src/OpenGL/libGLESv2/libGLESv2.vcxproj

diff --git a/src/OpenGL/libGLESv2/libGLESv2.vcxproj b/src/OpenGL/libGLESv2/libGLESv2.vcxproj
index 7bba1e6..53592e9 100644
--- a/src/OpenGL/libGLESv2/libGLESv2.vcxproj
+++ b/src/OpenGL/libGLESv2/libGLESv2.vcxproj
@@ -339,6 +339,7 @@
     <ClCompile Include="Texture.cpp" />

     <ClCompile Include="TransformFeedback.cpp" />

     <ClCompile Include="utilities.cpp" />

+    <ClCompile Include="VertexArray.cpp" />

     <ClCompile Include="VertexDataManager.cpp" />

   </ItemGroup>

   <ItemGroup>