Copy syscall.tbl and syscallhdr.sh from linux/arch/arm/tools/syscalls v5.5
Update syscallhdr.sh to generate QEMU syscall_nr.h

Update syscall.c to manage TARGET_NR_arm_sync_file_range as it has
replaced TARGET_NR_sync_file_range2

Move existing stuff from linux-user/Makefile.objs to
linux-user/arm/Makefile.objs

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200310103403.3284090-9-laurent@vivier.eu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>