Change header of khrplatform.h to point to the EGL-Registry repository
as its canonical location, and where to file issues and pull requests.

Also, refer to the git commit ID of the last meaningful modification of
the header, instead of using Subversion keywords that are not expanded
by git.

Fixes #21
diff --git a/api/KHR/khrplatform.h b/api/KHR/khrplatform.h
index 1ad3554..975bbff 100644
--- a/api/KHR/khrplatform.h
+++ b/api/KHR/khrplatform.h
@@ -2,7 +2,7 @@
 #define __khrplatform_h_
 
 /*
-** Copyright (c) 2008-2009 The Khronos Group Inc.
+** Copyright (c) 2008-2018 The Khronos Group Inc.
 **
 ** Permission is hereby granted, free of charge, to any person obtaining a
 ** copy of this software and/or associated documentation files (the
@@ -26,18 +26,16 @@
 
 /* Khronos platform-specific types and definitions.
  *
- * $Revision: 32517 $ on $Date: 2016-03-11 02:41:19 -0800 (Fri, 11 Mar 2016) $
+ * The master copy of khrplatform.h is maintained in the Khronos EGL
+ * Registry repository at https://github.com/KhronosGroup/EGL-Registry
+ * The last semantic modification to khrplatform.h was at commit ID:
+ *      67a3e0864c2d75ea5287b9f3d2eb74a745936692
  *
  * Adopters may modify this file to suit their platform. Adopters are
  * encouraged to submit platform specific modifications to the Khronos
  * group so that they can be included in future versions of this file.
- * Please submit changes by sending them to the public Khronos Bugzilla
- * (http://khronos.org/bugzilla) by filing a bug against product
- * "Khronos (general)" component "Registry".
- *
- * A predefined template which fills in some of the bug fields can be
- * reached using http://tinyurl.com/khrplatform-h-bugreport, but you
- * must create a Bugzilla login first.
+ * Please submit changes by filing pull requests or issues on
+ * the EGL Registry repository linked above.
  *
  *
  * See the Implementer's Guidelines for information about where this file