Bug#27259654 - ISSUES FOUND BY PVS-STUDIO STATIC ANALYZER

DESCRIPTION
===========
PVS-Studio static code analyzer found several suspicious
fragments of code across various files.

i)   sizeof() is using the pointer
ii)  memcpy() doesn't copy the whole string.
iii) enumeration constant 'wkb_multilinestring' is used as
     a variable of a Boolean-type.
iv) 'throw' keyword is missing from std::runtime_error()

FIX
===
i)   Use sizeof({actual object/data type})
ii)  Use strncpy() and set last char as '\0'
iii) N/A (Issue has already been fixed)
iv)  Add 'throw' before the exception.

RB: 21502

Author: Anushree Prakash B

libmysql/authentication_win/common.cc

@@ -1,4 +1,4 @@
-/* Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2011, 2019, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -504,7 +504,7 @@ const char* get_last_error_message(Error_message_buf buf)
   buf[0]= '\0';
   FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
 		NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-		(LPTSTR)buf, sizeof(buf), NULL );
+		(LPTSTR)buf, sizeof(Error_message_buf), NULL);
 
   return buf;
 }