error C2397: conversion from 'size_t' to 'BYTE (64 bit MSVC 2015)

Within the last day or so, the 64-bit version stop building. Now I'm getting the following error:
[build CXX] canvas/source/directx/dx_canvasbitmap.cxx
cl : Command line warning D9025 : overriding '/DNOMINMAX' with '/UNOMINMAX'
MathMLSolverPrecompiled.o : warning LNK4221: This object file does not define any previously 
undefined public symbols, so it will not be used by any link operation that consumes this library
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: E:\cygwin\home\Hearthstone\lode\dev\core\ridljar\com\sun\star\lib\util\WeakMap.java uses 
unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
[build CXX] canvas/source/directx/dx_canvasfont.cxx
cl : Command line warning D9025 : overriding '/DNOMINMAX' with '/UNOMINMAX'
COLLADASaxFWLPrecompiledHeaders.o : warning LNK4221: This object file does not define any 
previously undefined public symbols, so it will not be used by any link operation that consumes 
this library
COLLADAFWPrecompiledHeaders.o : warning LNK4221: This object file does not define any previously 
undefined public symbols, so it will not be used by any link operation that consumes this library
E:/core/canvas/source/directx/dx_canvasbitmap.cxx(71): error C2397: conversion from 'size_t' to 
'BYTE' requires a narrowing conversion
[build CXX] canvas/source/directx/dx_canvashelper.cxx
cl : Command line warning D9025 : overriding '/DNOMINMAX' with '/UNOMINMAX'
E:/core/solenv/gbuild/LinkTarget.mk:189: recipe for target 
'E:/core/workdir/CxxObject/canvas/source/directx/dx_canvasbitmap.o' failed
make[1]: *** [E:/core/workdir/CxxObject/canvas/source/directx/dx_canvasbitmap.o] Error 2
make[1]: *** Waiting for unfinished jobs....
Makefile:257: recipe for target 'build' failed
make: *** [build] Error 2
The following commit looks suspicious: 
https://cgit.freedesktop.org/libreoffice/core/commit/?id=03ddce193b3a031d9156775a8ee94206ba5b39ce

Is there any chance we could add a 64-bit Windows platform for Jenkins to build on? I've been 
trying to bisect a separate older 64-bit Windows bug. What should have been a simple bisect is 
turning into a project because of all of the cherry-picking/reverting that I've needed to do. A 
Jenkins bot would save us a lot of work.