How to cross-compile a Chromium Embedded Framework (CEF) Windows app on Linux using MinGW - cmake

Question

I'm trying to compile the cefclient and cefsimple applications provided in the CEF3 distribution into Windows executables from my Linux machine.
I'm running Linux Mint 17 (64-bit), and I'm trying to compile the Windows 32-bit versions of cefclient and cefsimple from Branch 2454.
I have cmake and the MinGW cross-compilers installed, and I tested each individually. They all work well. I also have the build-essential, libgtk2.0-dev, and libgtkglext1-dev dependencies installed.
When I try to build the MakeFiles from a new CEF/build directory, I get an error:
Command:
> cmake -G "Unix Makefiles" -D CMAKE_C_COMPILER=i686-w64-mingw32-gcc -D CMAKE_CXX_COMPILER=i686-w64-mingw32-g++ ..
CMakeError.log
Determining if the C compiler works failed with the following output:
Change Dir: /path/to/CEF/Source/build/CMakeFiles/CMakeTmp
Run Build Command:/usr/bin/make "cmTryCompileExec1497229498/fast"
/usr/bin/make -f CMakeFiles/cmTryCompileExec1497229498.dir/build.make CMakeFiles/cmTryCompileExec1497229498.dir/build
make[1]: Entering directory '/path/to/CEF/Source/build/CMakeFiles/CMakeTmp'
/usr/bin/cmake -E cmake_progress_report /path/to/CEF/Source/build/CMakeFiles/CMakeTmp/CMakeFiles 1
Building C object
CMakeFiles/cmTryCompileExec1497229498.dir/testCCompiler.c.o
/usr/bin/i686-w64-mingw32-gcc -o
CMakeFiles/cmTryCompileExec1497229498.dir/testCCompiler.c.o -c /path/to/CEF/Source/build/CMakeFiles/CMakeTmp/testCCompiler.c
Linking C executable cmTryCompileExec1497229498
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTryCompileExec1497229498.dir/link.txt --verbose=1
/usr/bin/i686-w64-mingw32-gcc CMakeFiles/cmTryCompileExec1497229498.dir/testCCompiler.c.o -o cmTryCompileExec1497229498 -rdynamic
i686-w64-mingw32-gcc: error: unrecognized command line option '-rdynamic'
make[1]: *** [cmTryCompileExec1497229498] Error 1
make[1]: Leaving directory `/path/to/CEF/Source/build/CMakeFiles/CMakeTmp'
make: *** [cmTryCompileExec1497229498/fast] Error 2
This is my first attempt to cross-compile anything from Linux to Windows. Am I doing it wrong? Is there something I'm missing? What is the error message indicating?