define WIN32_LEAN_AND_MEAN on mingw #224

Job	Run time
build (ubuntu-latest, clean, i386-pc-msdosdjgpp, binutils gcc djgpp-2.05 watt32)	16m 21s
build (ubuntu-latest, clean, i386-pc-msdosdjgpp, binutils gcc djgpp-cvs watt32)	16m 25s
build (ubuntu-latest, clean, i386-pc-msdosdjgpp, gdb)	4m 42s
build (ubuntu-latest, clean, arm-eabi, binutils gcc newlib)	21m 52s
build (ubuntu-latest, clean, arm-eabi, gdb)	6m 33s
build (ubuntu-latest, clean, avr, binutils gcc avr-libc)	35m 16s
build (ubuntu-latest, clean, avr, gdb avarice simulavr avrdude)	59s
build (ubuntu-latest, clean, ia16-elf, binutils gcc newlib)	5m 34s
build (macos-latest, clean, i386-pc-msdosdjgpp, binutils gcc djgpp-2.05 watt32)	31m 16s
build (macos-latest, clean, i386-pc-msdosdjgpp, binutils gcc djgpp-cvs watt32)	29m 38s
build (macos-latest, clean, i386-pc-msdosdjgpp, gdb)	3m 49s
build (macos-latest, clean, arm-eabi, binutils gcc newlib)	1h 0m 41s
build (macos-latest, clean, arm-eabi, gdb)	6m 7s
build (macos-latest, clean, avr, binutils gcc avr-libc)	1h 47m 20s
build (macos-latest, clean, avr, gdb avarice simulavr avrdude)	3m 34s
build (macos-latest, clean, ia16-elf, binutils gcc newlib)	9m 38s
	5h 59m 45s

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