Install SITL problem

I followed the instructions in
dev.ardupilot.com/wiki/sitl-nati … _in_cygwin

I am able to
make px4-v2

The paths are set correctly in .bashrc
export PATH=$PATH:$HOME/ardupilot/Tools/autotest

However,
make sitl -j4
generates the following error:

$ make sitl -j4 %% libraries/AP_Common/c++.o %% libraries/AP_Common/AP_Common.o %% libraries/AP_Menu/AP_Menu.o In file included from /home/Me/ardupilot/libraries/AP_Common/c++.cpp:9:0: /home/Me/ardupilot/libraries/AP_HAL/AP_HAL.h:6:21: fatal error: stdbool.h: No such file or directory compilation terminated. C:/cygwin/home/Me/ardupilot/mk/build_rules.mk:27: recipe for target '/tmp/arducopter.build/libraries/AP_Common/c++.o' failed make: *** [/tmp/arducopter.build/libraries/AP_Common/c++.o] Error 1 make: *** Waiting for unfinished jobs.... In file included from /home/Me/ardupilot/libraries/AP_Common/AP_Common.cpp:21:0: /home/Me/ardupilot/libraries/AP_HAL/AP_HAL.h:6:21: fatal error: stdbool.h: No such file or directory compilation terminated. C:/cygwin/home/Me/ardupilot/mk/build_rules.mk:27: recipe for target '/tmp/arducopter.build/libraries/AP_Common/AP_Common.o' failed make: *** [/tmp/arducopter.build/libraries/AP_Common/AP_Common.o] Error 1 // BUILDROOT=/tmp/arducopter.build HAL_BOARD=HAL_BOARD_SITL HAL_BOARD_SUBTYPE=HAL_BOARD_SUBTYPE_NONE TOOLCHAIN=NATIVE EXTRAFLAGS=-DGIT_VERSION="c52f16b8" In file included from /home/Me/ardupilot/libraries/AP_Common/AP_Common.h:26:0, from /home/Me/ardupilot/libraries/AP_Menu/AP_Menu.cpp:7: /usr/include/stdlib.h:16:20: fatal error: stddef.h: No such file or directory compilation terminated. C:/cygwin/home/Me/ardupilot/mk/build_rules.mk:27: recipe for target '/tmp/arducopter.build/libraries/AP_Menu/AP_Menu.o' failed make: *** [/tmp/arducopter.build/libraries/AP_Menu/AP_Menu.o] Error 1