Thank you that was informative. But even taking that into account the library seems to be too large for inclusion. Here are the memory stats without emWin:
$ /opt/K64F_sdk-sumo/gcc-arm-none-eabi-7-2019-q2-update/bin/arm-none-eabi-size MyExeBefore
text data bss dec hex filename
399296 3960 7980 411236 64664 MyExeBefore
And here with the emWin library (I had to expand regions in my .ld file just to all this to build):
$ /opt/K64F_sdk-sumo/gcc-arm-none-eabi-7-2019-q2-update/bin/arm-none-eabi-size MyExeAfter
text data bss dec hex filename
3273664 4008 2629884 5907556 5a2464 MyExeAfter
Perhaps the linker is not removing unreferenced code and data?