I often notice this failing during a build everything compiles and builds and kivy works fine regardless but it looks like quite a major failure even though everything works out.
just thought i would report it incase its significant :)
building 'kivy.graphics.opengl' extension
creating build
creating build/temp.linux-x86_64-2.7
creating build/temp.linux-x86_64-2.7/kivy
creating build/temp.linux-x86_64-2.7/kivy/graphics
arm-linux-androideabi-gcc -DANDROID -mandroid -fomit-frame-pointer --sysroot /home/oly/.buildozer/android/platform/android-ndk-r9d/platforms/android-14/arch-arm -DNDEBUG -DANDROID -mandroid -fomit-frame-pointer --sysroot /home/oly/.buildozer/android/platform/android-ndk-r9d/platforms/android-14/arch-arm -fPIC -I/home/oly/.buildozer/android/platform/android-ndk-r9d/platforms/android-14/arch-arm/usr/include -I/home/oly/repos/testing/enable-ctypes/build/python-install/include/python2.7 -c kivy/graphics/opengl.c -o build/temp.linux-x86_64-2.7/kivy/graphics/opengl.o
arm-linux-androideabi-gcc: error: kivy/graphics/opengl.c: No such file or directory
arm-linux-androideabi-gcc: fatal error: no input files
compilation terminated.
error: command 'arm-linux-androideabi-gcc' failed with exit status 1