Added the OpenVR license to openvr_capi.h

License taken from https://github.com/ValveSoftware/openvr/blob/master/LICENSE

src/video/openvr/openvr_capi.h

@@ -1,4 +1,33 @@
-//======= Copyright (c) Valve Corporation, All rights reserved. ===============
+/*
+  Copyright (c) 2015, Valve Corporation
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without modification,
+  are permitted provided that the following conditions are met:
+
+  1. Redistributions of source code must retain the above copyright notice, this
+     list of conditions and the following disclaimer.
+
+  2. Redistributions in binary form must reproduce the above copyright notice,
+     this list of conditions and the following disclaimer in the documentation and/or
+     other materials provided with the distribution.
+
+  3. Neither the name of the copyright holder nor the names of its contributors
+     may be used to endorse or promote products derived from this software without
+     specific prior written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+//=============================================================================
 //
 // Purpose: Header for flatted SteamAPI. Use this for binding to other languages.
 // This file is auto-generated, do not edit it.