VMS: Copy DECC inclusion epi- and prologues to internals

Because many of our test programs use internal headers, we need to make
sure they know how, exactly, to mangle the symbols.  So far, we've done
so by specifying it in the affected test programs, but as things change,
that will develop into a goose chase.  Better then to declare once and
for all how symbols belonging in our libraries are meant to be treated,
internally as well as publically.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3259)

crypto/include/internal/__DECC_INCLUDE_EPILOGUE.H

+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * This file is only used by HP C on VMS, and is included automatically
+ * after each header file from this directory
+ */
+
+/* restore state.  Must correspond to the save in __decc_include_prologue.h */
+#pragma names restore

crypto/include/internal/__DECC_INCLUDE_PROLOGUE.H

+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * This file is only used by HP C on VMS, and is included automatically
+ * after each header file from this directory
+ */
+
+/* save state */
+#pragma names save
+/* have the compiler shorten symbols larger than 31 chars to 23 chars
+ * followed by a 8 hex char CRC
+ */
+#pragma names as_is,shortened

include/internal/__DECC_INCLUDE_EPILOGUE.H

+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * This file is only used by HP C on VMS, and is included automatically
+ * after each header file from this directory
+ */
+
+/* restore state.  Must correspond to the save in __decc_include_prologue.h */
+#pragma names restore

include/internal/__DECC_INCLUDE_PROLOGUE.H

+/*
+ * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * This file is only used by HP C on VMS, and is included automatically
+ * after each header file from this directory
+ */
+
+/* save state */
+#pragma names save
+/* have the compiler shorten symbols larger than 31 chars to 23 chars
+ * followed by a 8 hex char CRC
+ */
+#pragma names as_is,shortened