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

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

build3/premake4.lua

@@ -45,6 +45,13 @@
 		description = "Try to link and use system X11 headers instead of dynamically loading X11 (dlopen is default)"
 	}
 
+	newoption
+	{
+		trigger = "enable_static_vr_plugin",
+		description = "Statically link vr plugin (in examples/SharedMemory/plugins/vrSyncPlugin)"
+	}
+
+
 	newoption
 	{
 		trigger = "noopengl3",
@@ -276,6 +283,11 @@ end
 	if not _OPTIONS["glfw_lib_name"] then
 		_OPTIONS["glfw_lib_name"] = default_glfw_lib_name
 	end	
+
+	if (_OPTIONS["enable_static_vr_plugin"]) then
+		defines("STATIC_LINK_VR_PLUGIN")
+	end
+
 	newoption
     {
 			trigger     = "glfw_include_dir",