The generic kernel-features.h defines __ASSUME_COPY_FILE_RANGE for 4.5
and later kernels. However, for 32-bit Arm binaries running on 64-bit
Arm kernels, the syscall was only wired up in the 4.7 kernel, although
the 32-bit Arm kernel had the syscall from 4.5 onwards. This patch
corrects the Arm kernel-features.h to undefine the macro for
configured minimum kernel versions before 4.7.
Tested (compilation only) with a build-many-glibcs.py build for
arm-linux-gnueabi.