Prepare for 1.1.1-pre6-dev

Reviewed-by: NMatt Caswell <matt@openssl.org>

README

 
- OpenSSL 1.1.1-pre5 (beta) 17 Apr 2018
+ OpenSSL 1.1.1-pre6-dev
 
  Copyright (c) 1998-2018 The OpenSSL Project
  Copyright (c) 1995-1998 Eric A. Young, Tim J. Hudson

include/openssl/opensslv.h

@@ -39,8 +39,8 @@ extern "C" {
  * (Prior to 0.9.5a beta1, a different scheme was used: MMNNFFRBB for
  *  major minor fix final patch/beta)
  */
-# define OPENSSL_VERSION_NUMBER  0x10101005L
-# define OPENSSL_VERSION_TEXT    "OpenSSL 1.1.1-pre5 (beta) 17 Apr 2018"
+# define OPENSSL_VERSION_NUMBER  0x10101006L
+# define OPENSSL_VERSION_TEXT    "OpenSSL 1.1.1-pre6-dev  xx XXX xxxx"
 
 /*-
  * The macros below are to be used for shared library (.so, .dll, ...)