premake4 add option --enable_static_vr_plugin to statically link the VR sync plugin

fix texture caching from previous commit (what happened there?)

examples/ExampleBrowser/premake4.lua

@@ -175,6 +175,11 @@ if (hasCL and findOpenGL3()) then
 				"../OpenCL/rigidbody/GpuRigidBodyDemo.cpp",
 			}
 		end
+		
+if (_OPTIONS["enable_static_vr_plugin"]) then
+		files {"../../examples/SharedMemory/plugins/vrSyncPlugin/vrSyncPlugin.cpp"}
+end
+
 if os.is("Linux") then
         initX11()
 end