bitcoin/bitcoin — pull request #4810 by ENikS (2014-09-02 00:02:52+00:00)
Title: Fixing Compiler Error C2466 on MSVC toolset building key.cpp

Construct char vchZero[0] = {}; is illegal on Microsoft compiler. The constant expression for the array size must be an integer greater than zero. For more info please see: http://msdn.microsoft.com/en-us/library/6zxfydcs.aspx

Adding one element seams to be quick and safe fix.