Win32: function pointers use C calling convention unless explicitly set to use

stdcall. The 'split' function pointer in ap_buckets.h points to both static functions
(which use C calling convention) and exported functions (which normally use stdcall).
Let's settle on using the C calling convention.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86130 13f79535-47bb-0310-9956-ffa450edef68